Abstract:

A rail road freight car truck has a truck bolster and a pair of side
frames, the truck bolster being mounted transversely relative to the side
frames. The mounting interface between the ends of the axles and the
sideframe pedestals allows lateral rocking motion of the sideframes in
the manner of a swing motion truck. The lateral swinging motion is
combined with a longitudinal self steering capability. The self steering
capability may be obtained by use of a longitudinally oriented rocker
that may tend to permit resistance to deflection that is proportional to
the weight carried across the interface. The truck may have auxiliary
centering elements mounted in the pedestal seats, and those auxiliary
centering elements may be made of resilient elastomeric material. The
truck may also have friction dampers that have a disinclination to
stick-slip behavior. The friction dampers may be provided with brake
linings, or similar features, on the face engaging the sideframe columns,
on the slope face, or both. The friction dampers may operate to yield
upward and downward friction forces that are not overly unequal. The
friction dampers may be mounted in a four-cornered arrangement at each
end of the truck bolster. The spring groups may include sub-groups of
springs of different heights.

Claims:

1. A damper assembly for installation between a truck bolster and a
sideframe of a three piece railroad car truck, said damper assembly
having a damper body and a friction member mountable to the damper body,
said damper body being adapted to seat in a damper pocket defined in the
bolster, and having a spring seat for engagement by a damper biasing
spring, said friction member having a friction surface for engagement
with mutually engaging surface of a wear plate when said biasing spring
works against said damper body; and said friction member having at least
two rotational degrees of freedom relative to said damper body when
mounted thereto, said two rotational degrees of freedom permitting said
friction member to rotate relative to said damper body to accommodate
both pitching and yawing of the sideframe relative to the bolster when
said damper assembly is installed.

2. The damper assembly of claim 1 wherein said damper body and said
friction member have mutually engaging arcuate surfaces, those surfaces
being formed on a body of revolution.

3. The damper assembly of claim 1 wherein said damper body and said
friction member have mutually engaging arcuate surfaces, those surfaces
being formed on a spherical arc.

4. The damper assembly of claim 1 wherein said mutually engaging surfaces
are in a non-rocking relationship.

5. The damper assembly of claim 1 and the wear plate, wherein said
mutually engaging surfaces are mounted in a sliding relationship.

6. The damper assembly of claim 1 and the damper biasing spring.

7. The damper assembly of claim 1 wherein said body includes a sloped face
for seating against an inclined face of the damper pocket, and said slope
face is free of a crown.

8. The damper assembly of claim 1 wherein said friction member includes a
first portion for engagement with said damper body, and a second portion
for engagement with the wear plate, and said second portion is made from
a different material than said first portion.

9. The damper assembly of claim 1 wherein said friction member has a
bulging portion thereof, and said damper body includes a cavity for
accommodating said bulging portion of said friction member.

10. The damper assembly of claim 1 wherein said friction surface has a
circular footprint.

11. The combination of a railroad freight car truck sideframe, a railroad
freight car truck bolster and damper assemblies mounted to work
therebetween, said damper assemblies including a damper assembly
according to claim 1, wherein said sideframe is mounted to yaw
appreciably relative to said bolster.

12. The combination of claim 11 wherein said combination includes four of
said damper assemblies according to claim 1 mounted to work between said
bolster and said sideframe.

13. A railroad freight car truck incorporating the combination of claim
12, wherein said truck includes two of said sideframes, and said truck is
free of unsprung lateral cross-bracing therebetween.

14. A railroad freight car truck incorporating the combination of claim
12, wherein said truck includes two of said sideframes, said both of said
sideframes being mounted to yaw appreciably relative to said bolster,
each of said sideframes has a pair of first and second opposed sideframe
columns, said sideframe columns having respective wear plates against
which said damper assemblies bear in use, each said sideframe has a long
axis, and said wear plates are mounted perpendicularly to said long axis.

16. A railroad freight car truck incorporating the combination of claim 11
wherein:said railroad freight car truck includes two of said
sideframes;said bolster is mounted on respective first and second coil
spring groups carried by said sideframes;said sideframes are mounted to
swing sideways relative to said bolster, and have a lateral stiffness
opposing sideways swinging;said coil spring groups each have a lateral
spring shear stiffness; andwhen said truck is fully laded, said lateral
spring shear stiffness of each said spring group is greater than said
lateral stiffness opposing sideways swinging of the respective sideframe
upon which that spring group is carried.

17. The railroad freight car truck of claim 16 wherein:said truck includes
self-steering apparatus mounted in sideframe pedestals of said
sideframes;both of said sideframes are mounted to yaw appreciably
relative to said bolster;each of said sideframes has a pair of first and
second opposed sideframe columns;said sideframe columns have respective
wear plates against which said dampers bear in use;each said sideframe
has a long axis, andsaid wear plates are mounted perpendicularly to said
long axis.

18. A three-piece railroad freight car truck having:a bolster sprung
between a pair of first and second sideframes;said first and second
sideframes each having a pair of opposed first and second sideframe
columns, a tension member and a compression member;said sideframe
columns, tension member and compression member co-operating to define
respective sideframe windows of said first and second sideframes, each
said tension member having a lower spring seat defined thereon;said
sideframes having respective pedestal seats, bearing adapters mounted in
said pedestal seats, and wheelsets including bearings upon which said
bearing adapters seat;first and second main spring groups mounted on said
lower spring seats of said first and second sideframes respectively, said
first and second main spring groups being groups of coil springs mounted
in side-by-side arrangements;said bolster having first and second ends,
said first end being sprung on said first main spring group, and said
second end being sprung on said second main spring group;friction dampers
mounted to work between said bolster and said sideframes as said bolster
moves relative to said sideframes;said bolster being mounted to permit
limited lateral travel thereof relative to said sideframes,said truck
having co-operating members constraining said bolster to a first bounded
range of lateral travel relative to said sideframes when loaded under a
first magnitude of vertical load, and to a second, different, bounded
range of lateral travel relative to said sideframes under a second,
different magnitude of vertical load, said co-operating members defining
the bounds of said first and second bounded ranges of lateral travel.

19. The three piece railroad freight car truck of claim 18 wherein said
sideframes have lengthwise axes, said coil springs are arranged in rows
running lengthwise relative to said sideframes, said dampers are mounted
in damper pockets of said bolster and said sideframe columns have wear
plates against which said dampers slidingly bear in use, and said wear
plates are perpendicular to said lengthwise axes of said respective
sideframes.

20. The three piece railroad freight car truck of claim 18 wherein said
truck is a self steering truck.

21. The three piece railroad freight car truck of claim 20 wherein said
self-steering truck has a rocker interface between respective mating
pairs of said bearing adapters and said pedestals, and said rocker
interface includes a longitudinal rocker.

22. The three piece railroad freight car truck of claim 20 wherein said
dampers include first and second sets of dampers mounted at said first
and second ends of said bolster respectively, each of said sets of
dampers including four independently driven dampers.

23. The three piece railroad freight car truck of claim 18 wherein said
truck is free of unsprung lateral cross-bracing between said sideframes.

24. A three piece rail road car truck having a bolster mounted cross-wise
between two sideframes, the bolster having gibs bounding lateral movement
of said sideframe relative to said sideframes, said gibe being tapered to
permit a larger range of lateral travel when said truck is lightly laded
than when said truck is heavily laded; and said truck having friction
dampers mounted in bolster pockets in said bolster, said friction dampers
each having a damper body and a damper friction surface member, each said
damper being biased by a spring to bear against a sideframe column wear
plate of said truck, and each said damper friction surface member having
two rotational degrees of freedom relative to its respective damper body
to accommodate angular deflection in both yawing and pitching of each
said sideframe relative to said bolster.

25. (canceled)

Description:

[0001]This application is a continuation of U.S. application Ser. No.
11/002,222 filed Dec. 3, 2004, now U.S. Pat. No. 7,631,603, which is
hereby incorporated by reference.

FIELD OF THE INVENTION

[0002]This invention relates to the field of rail road cars, and, more
particularly, to the field of three piece rail road car trucks for rail
road cars.

BACKGROUND OF THE INVENTION

[0003]Rail road cars in North America commonly employ double axle
swiveling trucks known as "three piece trucks" to permit them to roll
along a set of rails. The three piece terminology refers to a truck
bolster and pair of first and second sideframes. In a three piece truck,
the truck bolster extends cross-wise relative to the sideframes, with the
ends of the truck bolster protruding through the sideframe windows.
Forces are transmitted between the truck bolster and the sideframes by
spring groups mounted in spring seats in the sideframes. The sideframes
carry forces to the sideframe pedestals. The pedestals seat on bearing
adapters, whence forces are carried in turn into the bearings, the axle,
the wheels, and finally into the tracks. The 1980 Car & Locomotive
Cyclopedia states at page 669 that the three piece truck offers
"interchangeability, structural reliability and low first cost but does
so at the price of mediocre ride quality and high cost in terms of car
and track maintenance."

[0004]Ride quality can be judged on a number of different criteria. There
is longitudinal ride quality, where, often, the limiting condition is the
maximum expected longitudinal acceleration experienced during humping or
flat switching, or slack run-in and run-out. There is vertical ride
quality, for which vertical force transmission through the suspension is
the key determinant. There is lateral ride quality, which relates to the
lateral response of the suspension. There are also other phenomena to be
considered, such as truck hunting, the ability of the truck to self
steer, and, whatever the input perturbation may be, the ability of the
truck to damp out undesirable motion. These phenomena tend to be
inter-related, and the optimization of a suspension to deal with one
phenomenon may yield a system that may not necessarily provide optimal
performance in dealing with other phenomena.

[0005]In terms of optimizing truck performance, it may be advantageous to
be able to obtain a relatively soft dynamic response to lateral and
vertical perturbations, to obtain a measure of self steering, and yet to
maintain resistance to lozenging (or parallelogramming). Lozenging, or
parallelogramming, is non-square deformation of the truck bolster
relative to the side frames of the truck as seen from above. Self
steering may tend to be desirable since it may reduce drag and may tend
to reduce wear to both the wheels and the track, and may give a smoother
overall ride.

[0006]Among the types of truck discussed in this application are swing
motion trucks. An earlier patent for a swing motion truck is U.S. Pat.
No. 3,670,660 of Weber et al., issued Jun. 20, 1972. This truck has
unsprung lateral cross bracing, in the nature of a transom that links the
sideframes together. By contrast, the description that follows describes
several embodiments of truck that do not employ lateral unsprung
cross-members, but that may use damper elements mounted in a
four-cornered arrangement at each end of the truck bolster. An earlier
patent for dampers is U.S. Pat. No. 3,714,905 of Barber, issued Feb. 6,
1973.

SUMMARY OF THE INVENTION

[0007]The present invention may provide a rail road car truck with
bi-directional rocking at the sideframe pedestal to wheelset axle end
interface. It may also provide a truck that has self steering that is
proportional to the weight carried by the truck. It may further have a
longitudinal rocker at the sideframe to axle end interface. Further it
may provide a swing motion truck with self steering. It may also provide
a swing motion truck that has the combination of a swing motion lateral
rocker and an elastomeric bearing adapter pad.

[0008]In an aspect of the invention, there is a wheelset-to-sideframe
interface assembly for a railroad car truck. The interface assembly has a
bearing adapter and a mating pedestal seat. The bearing adapter has first
and second ends that form an interlocking insertion between a pair of
pedestal jaws of a railroad car sideframe. The bearing adapter has a
first rocking member. The pedestal seat has a second rocking member. The
first and second rocking members are matingly engageable to permit
lateral and longitudinal rocking between them. There is a resilient
member mounted between the bearing adapter and pedestal seat. The
resilient member has a portion formed that engages the first end of the
bearing adapter. The resilient member has an accommodation formed to
permit the mating engagement of the first and second rocking members.

[0009]In a feature of that aspect of the invention, the resilient member
has the first and second ends formed for interposition between the
bearing adapter and the pedestal jaws of the sideframe. In another
feature, the resilient member has the form of a Pennsy Pad with a relief
formed to define the accommodation. In a further feature, the resilient
member is an elastomeric member. In yet another feature, the elastomeric
member is made of rubber material. In still another feature, the
elastomeric member is made of a polyurethane material. In yet a further
feature, the accommodation is formed through the elastomeric material and
the first rocking member protrudes at least part way through the
accommodation to meet the second rocking member. In an additional
feature, the bearing adapter is a bearing adapter assembly which includes
a bearing adapter body surmounted by the first rocker member. In another
additional feature, the first rocker member is formed of a different
material from the bearing body. In a further additional feature, the
first rocker member is an insert.

[0010]In yet another additional feature, the first rocker member has a
footprint with a profile conforming to the accommodation. In still
another additional feature, the profile and the accommodation are
mutually indexed to discourage mis-orientation of the first rocker member
relative to the bearing adapter. In yet a further additional feature, the
body and the first rocker member are keyed to discourage mis-orientation
between them. In a further feature, the accommodation is formed through
the resilient member and the second rocking member protrudes at least
part way through said accommodation to meet the first rocking member. In
another further feature, the pedestal seat includes an insert with the
second rocking member formed in it. In yet another further feature, the
second rocker member has a footprint with a profile conforming to the
accommodation.

[0011]In still a further feature, the portion of the resilient member that
is formed to engage the first end of the bearing adapter, when installed,
includes elements that are interposed between the first end of the
bearing adapter and the pedestal jaw to inhibit lateral and longitudinal
movement of the bearing adapter relative to the jaw.

[0012]In another aspect of the invention the ends of the bearing adapter
includes an end wall bracketed by a pair of corner abutments. The end
wall and corner abutments define a channel to permit the sliding
insertion of the bearing adapter between the pedestal jaw of the
sideframe. The portion of the resilient member that is formed to engage
the first end of the bearing adapter is the first end portion. The
resilient member has a second end portion that is formed to engage the
second end of the bearing adapter. The resilient member has a middle
portion that extends between the first and second end portions. The
accommodation is formed in the middle portion of the resilient member. In
another feature, the resilient member has the form of a Pennsy Pad with a
central opening formed to define the accommodation.

[0013]In another aspect of the invention, a wheelset-to-sideframe
interface assembly for a rail road car truck has an interface assembly
that has a bearing adapter, a pedestal seat and a resilient member. The
bearing adapter has a first end and a second end that each have a end
wall bracketed by a pair of corner abutments. The end wall and corner
abutments co-operate to define a channel that permits insertion of the
bearing adapter between a pair of thrust lugs of a sidewall pedestal. The
bearing adapter has a first rocking member. The pedestal seat has a
second rocking member to make engagement with the first rocking member.
The first and second rocking members, when engaged, are operable to rock
longitudinally relative to the sideframe to permit the rail road car
truck to steer. The resilient member has a first end portion that is
engageable with the first end of the bearing adapter for interposition
between the first end of the bearing adapter and the first pedestal jaw
thrust lug. The resilient member has a second end portion that is
engageable with the second end of the bearing adapter for interposition
between the second end of the bearing adapter and the second pedestal jaw
thrust lug. The resilient member has a medial portion lying between the
first and second end portions. The medial portion is formed to
accommodate mating rocking engagement of the first and second rocking
members.

[0014]In another feature, there is a resilient pad that is used with the
bearing adapter which has a rocker member for mating and the rocking
engagement with the rocker member of the pedestal seat. The resilient pad
has a first portion for engaging the first end of the bearing adapter, a
second portion for engaging a second end of the bearing adapter and a
medial portion between the first and second end portions. The medial
portion is formed to accommodate mating engagement of the rocker members.

[0015]In a feature of the aspect of the invention there is a
wheelset-to-sideframe assembly kit that has a pedestal seat for mounting
in the roof of a rail road car truck sideframe pedestal. There is a
bearing adapter for mounting to a bearing of a wheelset of a rail road
car truck and a resilient member for mounting to the bearing adapter. The
bearing adapter has a first rocker element for engaging the seat in
rocking relationship. The bearing adapter has a first end and a second
end, both ends having an endwall and a pair of abutments bracketing the
end wall to define a channel, that permits sliding insertion of the
bearing adapter between a pair of sideframe pedestal jaw thrust lugs. The
resilient member has a first portion that conforms to the first end of
the bearing adapter for interpositioning between the bearing adapter and
a thrust lug. The resilient member has a second portion connected to the
first portion that, as installed, at least partially overlies the bearing
adapter.

[0016]In another feature, the wheelset-to-sideframe assembly kit has a
second portion of the resilient member with a margin that has a profile
facing toward the first rocker element. The first rocker element is
shaped to nest adjacent to the profile. In a further feature,
wheelset-to-sideframe assembly kit has a bearing adapter that includes a
body and the first rocker element is separable from that body. In still
another feature, the wheelset-to-sideframe assembly kit has a second
portion of the resilient member with a margin that has a profile facing
toward the first rocker element which is shaped to nest adjacent the
profile. In yet still another feature, the wheelset-to-sideframe assembly
kit has a profile and first rocker element shaped to discourage
mis-orientation of the first rocker element when installed. In another
feature, the wheelset-to-sideframe assembly kit has a first rocker
element with a body that is mutually keyed to facilitate the location of
the first rocker element when installed. In still another feature, the
wheelset-to-sideframe assembly kit has a first rocker element and body
that are mutually keyed to discourage mis-orientation of the rocker
element when installed. In yet still another feature, the
wheelset-to-sideframe assembly kit has a first rocker element and a body
with mutual engagement features. The features are mutually keyed to
discourage mis-orientation of the rocker element when installed.

[0017]In a further feature, the kit has a second resilient member that
conforms to the second end of the bearing adapter. In another feature,
the wheelset-to-sideframe assembly kit includes a pedestal seat
engagement fitting for locating the resilient feature relative to the
pedestal seat on the assembly. In yet still another feature, the
resilient member includes a second end portion that conforms to the
second end of the bearing adapter.

[0018]In an additional feature, there is a bearing adapter for
transmitting load between the wheelset bearing and a sideframe pedestal
of a railroad car truck. It has at least a first and second land for
engaging the bearing and a relief formed between the first and second
land. The relief extends predominantly axially relative to the bearing.
In another additional feature, the lands are arranged in an array that
conforms to the bearing and the relief is formed at the apex of the
array. In still another additional feature, the bearing adapter includes
a second relief that extends circumferentially relative to the bearing.
In yet still another additional feature, the axially extending relief and
the circumferentially extending relief extends along a second axis of
symmetry of the bearing adapter.

[0019]In a further feature, the radially extending relief extends along a
first axis of symmetry of the bearing adapter and the circumferentially
extending relief extends along a second axis of symmetry of the bearing
adapter. In still a further feature, the bearing adapter has lands that
are formed on a circumferential arc. In yet still another feature, the
bearing adapter has a rocker element that has an upwardly facing rocker
surface. In yet still a further feature, the bearing adapter has a body
with a rocker element that is separable from the body.

[0020]In another aspect of the invention, there is a bearing adapter for
installation in a rail road car truck sideframe pedestal. The bearing
adapter has an upper portion engageable with a pedestal seat, and a lower
portion engageable with a bearing casing. The lower portion has an apex.
The lower portion includes a first land for engaging a first portion of
the bearing casing, and a second land region for engaging a second
portion of the bearing casing. The first land lies to one side of the
apex. The second land lies to the other side of the apex. At least one
relief located between the first and second lands.

[0021]In an additional feature, the relief has a major dimension oriented
to extend along the apex in a direction that runs axially relative to the
bearing when installed. In another feature, the relief is located at the
apex. In another feature there are at least two the reliefs, the two
reliefs lying to either side of a bridging member, the bridging member
running between the first and second lands.

[0022]In another aspect of the invention there is a kit for retro-fitting
a railroad car truck having elastomeric members mounted over bearing
adapters. The kit includes a mating bearing adapter and a pedestal seat
pair. The bearing adapter and the pedestal seat have co-operable
bi-directional rocker elements. The seat has a depth of section of
greater than 1/2 inches.

[0023]In another aspect of the invention, there is a railroad car truck
having a bolster and a pair of co-operating sideframes mounted on
wheelsets for rolling operation along railroad tracks. Truck has rockers
mounted between the sideframes to permit lateral swinging of the
sideframes. The truck is free of lateral unsprung cross-bracing between
the sideframes. The sideframes each have a lateral pendulum height, L,
measured between a lower location at which gravity loads are passed into
the sideframe, and an upper location at the rocker where a vertical
reaction is passed into the sideframes. The rocker includes a male
element having a radius of curvature, r1, and a ratio of r1:L is less
than 3.

[0024]In a further feature of that aspect, the rocker has a female element
in mating engagement with the male element. The female element has a
radius of curvature R1 that is greater than r1, and the factor
[(1/L.)/((1/r1)-(1/R1))] is less than 3. In another further
feature, R1 is at least 4/3 as large as r1, and r1 is
greater than 15 inches.

[0025]In an aspect of the present invention, there is a rail road car
truck that has a self steering capability and friction dampers in which
the co-efficients of static and dynamic friction are substantially
similar. It may include the added feature of lateral rocking at the
sideframe pedestal to wheelset axle end interface. It may include self
steering proportional to the weight carried by the truck. It may further
have a longitudinal rocker at the sideframe to axle end interface.
Further it may provide a swing motion truck with self steering. It may
also provide a swing motion truck that has the combination of a swing
motion lateral rocker and an elastomeric bearing adapter pad. In another
feature, the truck may have dampers lying along the longitudinal
centerline of the spring groups of the truck suspensions. In another
feature, it may include dampers mounted in a four cornered arrangement.
In another feature it may include dampers having modified friction
surfaces on both the friction bearing face and on the obliquely angled
face of the damper that seats in the bolster pocket.

[0026]In another aspect of the invention, a three piece rail road car
truck has a truck bolster mounted transversely between a pair of
sideframes. The truck bolster has ends, each of the ends being
resiliently mounted to a respective one of the sideframes. The truck has
a set of dampers mounted in a four cornered damper arrangement between
each the bolster end and its respective sideframe. Each damper has a
bearing surface mounted to work against a mating surface at a friction
interface in a sliding relationship when the bolster moves relative to
the sideframes. Each damper has a seat against which to mount a biasing
device for urging the bearing face against the mating surface. The
bearing surface of the damper has a dynamic co-efficient of friction and
a static co-efficient of friction when working against the mating
surface. The static and dynamic co-efficients of friction are of
substantially similar magnitude.

[0027]In a further feature of that aspect of the invention, the
co-efficients of friction have respective magnitudes within 10% of each
other. In another feature, the co-efficients of friction are
substantially equal. In another feature the co-efficients of friction lie
in the range of 0.1 to 0.4. In still another feature, the co-efficients
of friction lie in the range 0.2 to 0.35. In a further feature, the
co-efficients of friction are about 0.30 (+/-10%). In still another
feature, the dampers each include a friction element mounted thereto, and
the bearing surface is a surface of the friction element. In yet still
another feature, the friction element is a composite surface element that
includes a polymeric material.

[0028]In another feature of that aspect of the invention, the truck is a
self-steering truck. In another feature, the truck includes a bearing
adapter to sideframe pedestal interface that includes a self-steering
apparatus. In another feature, the self-steering apparatus includes a
rocker. In a further feature, the truck includes a bearing adapter to
sideframe pedestal interface that includes a self-steering apparatus
having a force-deflection characteristic varying as a function of
vertical load. In still another feature, the truck has a bearing adapter
to sideframe pedestal interface that includes a bi-directional rocker
operable to permit lateral rocking of the sideframes and to permit
self-steering of the truck.

[0029]In another feature of that aspect of the invention, each damper has
an oblique face for seating in a damper pocket of a truck bolster of a
rail road car truck, the bearing face is a substantially vertical face
for bearing against a mating sideframe column wear surface, and, in use,
the seat is oriented to face substantially downwardly. In another
feature, the oblique face has a surface treatment for encouraging sliding
of the oblique face relative to the damper pocket. In still another
feature, the oblique face has a static coefficient of friction and a
dynamic co-efficient of friction, and the co-efficients of static and
dynamic friction of the oblique face are substantially equal. In a
further feature, the oblique face and the bearing face both have sliding
surface elements, and both of the sliding surface elements are made from
materials having a polymeric component. In yet a further feature, the
oblique face has a primary angle relative to the bearing surface, and a
cross-wise secondary angle.

[0030]In another aspect of the invention, there is a three piece railroad
car truck having a bolster transversely mounted between a pair of
sideframes, and wheelsets mounted to the sideframes at wheelset to
sideframe interface assemblies. The wheelset to sideframe interface
assemblies are operable to permit self steering, and include apparatus
operable to urge the wheelsets in a lengthwise direction relative to the
sideframes to a minimum potential energy position relative to the
sideframes. The self-steering apparatus has a force deflection
characteristic that is a function of vertical load.

[0031]In a further aspect of the invention, there is a bearing adapter for
a railroad car truck. The bearing adapter has a body for seating upon a
bearing of a rail road truck wheelset, and a rocker member for mounting
to the body. The rocker member has a rocking surface, the rocking surface
facing away from the body when the rocker member is mounted to the body,
and the rocker being made of a different material from the body.

[0032]In a further feature of that aspect, the rocker member is made from
a tool steel. In another feature of that aspect of the invention, the
rocker member is made from a metal of a grade used for the fabrication of
ball bearings. In another feature, the body is made of cast iron. In
another feature, the rocker member is a bi-directional rocker member. In
still another feature, the rocking surface of the rocking member defines
a portion of a spherical surface.

[0033]In another aspect of the invention, there is a three piece railroad
car truck having rockers for self steering. In still another aspect,
there is a railroad car truck having a sideframe, an axle bearing, and a
rocker mounted between the sideframe and the axle bearing. The rocker has
a transverse axis to permit rocking of and the bearing lengthwise
relative to the sideframe.

[0034]In another aspect of the invention there is a three piece railroad
car truck having a bolster mounted transversely to a pair of sideframes.
The side frames have pedestal fittings and wheelsets mounted in the
pedestal fittings. The pedestal fittings include rockers. Each rocker has
a transverse axis to permit rocking in a lengthwise direction relative to
the sideframes.

[0035]In another aspect of the invention there is a three piece railroad
car truck having a truck bolster mounted transversely to a pair of side
frames, each sideframes has fore and aft pedestal seat interface
fittings, and a pair of wheelsets mounted to the pedestal seat interface
fittings. The pedestal seat interface fittings include rockers operable
to permit the truck to self steer.

[0036]In another aspect of the invention there is a railroad car truck
having a sideframe, an axle bearing, and a bi-directional rocker mounted
between the sideframe and the axle bearing. In still another aspect of
the invention, there is a railroad car truck having a truck bolster
mounted transversely between a pair of sideframes, and wheelsets mounted
to the sideframes to permit rolling operation of the truck along a set of
rail road tracks. The truck includes rocker elements mounted between the
sideframes and the wheelsets. The rocker elements are operable to permit
lateral swinging of the sideframes and to permit self-steering of the
truck.

[0037]In another aspect of the invention there is a railroad car truck
having a pair of sideframes, a pair of wheelsets having ends for mounting
to the sideframes, and sideframe to wheelset interface fittings. The
sideframe to wheelset interface fittings include rocking members having a
first degree of freedom permitting lateral swinging of the sideframes
relative to the wheelsets, and a second degree of freedom permitting
longitudinal rocking of the wheelset ends relative to the sideframes.

[0038]In another aspect of the invention there is a railroad car truck
having rockers formed on a compound curvature, the rockers being operable
to permit both a lateral swinging motion in the truck and self steering
of the truck. In still another aspect of the invention, there is a
railroad car truck having a pair of sideframes, a pair of wheelsets
having ends for mounting to the sideframes, and sideframe to wheelset
interface fittings. The sideframe to wheelset interface fittings include
rocking members having a first degree of freedom permitting lateral
swinging of the sideframes relative to the wheelsets, a second degree of
freedom permitting longitudinal rocking of the wheelset ends relative to
the sideframes. The wheelset to sideframe interface fittings being
torsionally compliant about a predominantly vertical axis.

[0039]In aspect of the invention there is a swing motion rail road car
truck modified to include rocking elements mounted to permit
self-steering. In yet another aspect there is a swing motion rail road
car truck having a transverse bolster sprung between a pair of side
frames, and a pair of wheelsets mounted to the sideframes at wheelset to
sideframe interface fittings. The wheelset to sideframe interface
fittings include swing motion rockers and elastomeric members mounted in
series with the swing motion rockers to permit the truck to self-steer.

[0040]In another aspect of the invention, there is a rail road car truck
having a truck bolster mounted transversely between a pair of sideframes,
and wheelsets mounted to the sideframes at wheelset to sideframe
interface fittings. The wheelset to sideframe interface fittings include
rockers for permitting lateral swinging motion of the sideframes. The
rockers have a male element and a mating female element. The male and
female rocker elements are engaged for co-operative rocking operation.
The female element has a radius of curvature in the lateral swinging
direction of less than 25 inches. The wheelset to sideframe interface
fittings are also operable to permit self steering.

[0041]In still another aspect of the invention there is a rail road car
truck having a truck bolster mounted transversely between a pair of
sideframes, and wheelsets mounted to the sideframes at wheelset to
sideframe interface fittings. The wheelset to sideframe interface
fittings include rockers for permitting lateral swinging motion of the
sideframes. The rockers have a male element and a mating female element.
The male and female rocker elements are engaged for co-operative rocking
operation. The sideframes have an equivalent pendulum length, Leq,
when mounted on the rocker, of greater than 6 inches. The wheelset to
sideframe interface fittings include an elastomeric member mounted in
series with the rockers to permit self steering.

[0042]In yet another aspect of the invention there is a rail road car
truck having a truck bolster mounted transversely between a pair of
sideframes, and wheelsets mounted to the sideframes at wheelset to
sideframe interface fittings. The wheelset to sideframe interface
fittings include rockers for permitting self steering of the truck. The
rockers have a male element and a mating female element. The male and
female rocker elements are engaged for co-operative rocking operation,
and the wheelset to sideframe interface fittings include an elastomeric
member mounted in series with the rockers.

[0043]In still another aspect of the invention there is a rail road car
truck having a transverse bolster sprung between two sideframes, and
wheelsets mounted to the sideframes at wheelset to sideframe interface
fittings, the truck having a spring groups and dampers seated in the
bolster and biased by the spring groups to ride against the sideframes.
The spring groups include a first damper biasing spring upon which a
first damper of the dampers seats. The first damper biasing spring has a
coil diameter. The first damper has a width of more than 150% of the coil
diameter.

[0044]In another aspect of the invention there is a rail road car truck
having a bolster having ends sprung from a pair of sideframes, and
wheelsets mounted to the sideframes at wheelset to sideframe interface
fittings. The wheelset to sideframe interface fittings include
bi-directional rocker fittings for permitting lateral swinging of the
sideframes and for permitting self steering of the wheelsets. The truck
has a four cornered arrangement of dampers mounted at each end of the
bolster. In a further feature of that aspect of the invention the
interface fittings are torsionally compliant about a predominantly
vertical axis.

[0045]In another aspect there is a railroad car truck having a bolster
transversely mounted between a pair of sideframes, and wheelsets mounted
to the sideframes. The rail road car truck has a bi-directional
longitudinal and lateral rocking interface between each sideframe and
wheelset, and four cornered damper groups mounted between each sideframe
and the truck bolster. In an additional feature of that aspect of the
invention the rocking interface is torsionally compliant about a
predominantly vertical axis. In another additional feature, the rocking
interface is mounted in series with a torsionally compliant member.

[0046]In yet another aspect of the invention there is a self-steering rail
road car truck having a transversely mounted bolster sprung between two
sideframes, and wheelsets mounted to the sideframes. The sideframes are
mounted to swing laterally relative to the wheelsets. The truck has
friction dampers mounted between the bolster and the sideframes. The
friction dampers have co-efficients of static friction and dynamic
friction. The co-efficients of static and dynamic friction being
substantially the same.

[0047]In still another aspect there is a self-steering rail road car truck
having a transversely mounted bolster sprung between two sideframes, and
wheelsets mounted to the sideframes. The sideframes are mounted to swing
laterally relative to the wheelsets. The truck has friction dampers
mounted between the bolster and the sideframes. The friction dampers have
co-efficients of static friction and dynamic friction. The co-efficients
of static and dynamic friction differ by less than 10%. Expressed
differently, the friction dampers having a co-efficient of static
friction, us, and a co-efficient of dynamic friction, uk, and a
ratio of us/uk lies in the range of 1.0 to 1.1. In another
aspect of the invention, the truck has friction dampers mounted between
the bolster and the sideframes in a sliding friction relationship that is
substantially free of stick-slip behavior. In another feature of that
aspect of the invention the friction dampers include friction damper
wedges having a first face for engaging one of the sideframes, and a
second, sloped, face for engaging a bolster pocket. The sloped face is
mounted in the bolster pocket in a sliding friction relationship that is
substantially free of stick-slip behavior.

[0048]In another aspect of the invention there is a self-steering rail
road car truck having a bolster mounted between a pair of sideframes, and
wheelsets mounted to the sideframes for rolling motion along railroad
tracks. The wheelsets are mounted to the sideframes at wheelset to
sideframe interface fittings. Those fittings are operable to permit
lateral rocking of the sideframes. The truck has a set of friction
dampers mounted between the bolster and each of the sideframes. The
friction dampers have a first face in sliding friction relationship with
the sideframes and a second face seated in a bolster pocket of the
bolster. The first face, when operated in engagement with the sideframe,
has a co-efficient of static friction and a co-efficient of dynamic
friction, the co-efficients of static and dynamic friction of the first
face differing by less than 10%. The second face, when mounted within the
bolster pocket, has a co-efficient of static friction, and a co-efficient
of dynamic friction, and the co-efficients of static and dynamic friction
of the second face differing by less than 10%.

[0049]In yet another aspect of the invention there is a self-steering rail
road car truck having a bolster mounted between a pair of sideframes, and
wheelsets mounted to the sideframes for rolling motion along railroad
tracks. The wheelsets are mounted to the sideframes at wheelset to
sideframe interface fittings. The interface fittings are operable to
permit lateral rocking of the sideframes. The truck has a set of friction
dampers mounted between the bolster and each of the sideframes. The
friction dampers have a first face in slidable friction relationship with
the sideframes and a second face seated in a bolster pocket of the
bolster. The first face and the side frame are co-operable and are in a
substantially stick-slip free condition. The second face and the bolster
pocket are also in a substantially stick-slip free condition.

[0050]In another aspect of the invention there is a rocker for a bearing
adapter of a rail road car truck. The rocker has a rocking surface for
rocking engagement with a mating surface of a pedestal seat of a
sideframe of a railroad car truck. The rocking surface has a compound
curvature to permit both lengthwise and sideways rocking. In a
complementary aspect of the invention, there is a rocker for a pedestal
seat of a sideframe of a rail road car truck. The rocker has a rocking
surface for rocking engagement with a mating surface of a bearing adapter
of a railroad car truck. The rocking surface has a compound curvature to
permit both lengthwise and sideways rocking.

[0051]In an aspect of the invention there is a sideframe pedestal to axle
bearing interface assembly for a three piece rail road car truck, the
interface assembly having fittings operable to rock both laterally and
longitudinally.

[0052]In an additional feature of that aspect of the invention the
assembly includes mating surfaces of compound curvature, the compound
curvature including curvature in both lateral and horizontal directions.
In another feature, the assembly includes at least one rocker element and
a mating element, the rocker and mating elements being in point contact
with a mating element, the element in point contact being movable in
rolling point contact with the mating element. In still another feature,
the element in point contact is movable in rolling point contact with the
mating element both laterally and longitudinally. In yet another feature,
the fittings include rockingly matable saddle surfaces.

[0053]In another feature, the fittings include a male surface having a
first compound curvature and a mating female surface having a second
compound curvature in rocking engagement with each other, and one of the
surfaces includes at least a spherical portion. In a further feature, the
fittings include a non-rocking central portion in at least one direction.
In still another feature, relative to a vertical axis of rotation,
rocking motion of the fittings longitudinally is torsionally de-coupled
from rocking of the fittings laterally. In a yet further feature the
fittings include a force transfer interface that is torsionally compliant
relative to torsional moments about a vertical axis. In still another
feature, the assembly includes an elastomeric member.

[0054]In another aspect of the invention, there is a swing motion three
piece rail road car truck having a laterally extending truck bolster, a
pair of longitudinally extending sideframes to which the truck bolster is
resiliently mounted, and wheelsets to which the side frames are mounted.
Damper groups are mounted between the bolster and each of the sideframes.
The damper groups each have a four-cornered damper layout, and wheelset
to sideframe pedestal interface assemblies operable to permit lateral
swinging motion of the sideframes and longitudinal self-steering of the
wheelsets.

[0055]In a further aspect there is a rail road car truck having a truck
bolster mounted between sideframes, and wheelsets to which the sideframes
are mounted, and wheelset to sideframe interface assemblies by which to
mount the sideframes to the wheelsets. The sideframe to wheelset
interface assemblies include rocking apparatus to permit the sideframes
to swing laterally. The rocking apparatus includes first and second
surfaces in rocking engagement. At least a portion of the first surface
has a first radius of curvature of less than 30 inches. The sideframe to
wheelset interface includes self steering apparatus.

[0056]In a feature of that aspect of the invention, the self steering
apparatus has a substantially linear force deflection characteristic. In
another feature, the self steering apparatus has a force-deflection
characteristic that varies with vertical loading of the sideframe to
wheelset interface assembly. In a further feature, the force-deflection
characteristic varies linearly with vertical loading of the sideframe to
wheelset interface assembly. In another feature, the self steering
apparatus includes a rocking element. In still another feature, the
rocking element includes a rocking member subject to angular displacement
about an axis transverse to one of the sideframes.

[0057]In another feature, the self steering apparatus includes male and
female rocking elements, and at least a portion of the male rocking
element has a radius of curvature of less than 45 inches. In still
another feature, the self steering apparatus includes male and female
rocking elements, and at least a portion of the female rocking element
has a radius of curvature of less than 60 inches. In still another
feature the self steering apparatus is self centering. In a further
feature, the self steering apparatus is biased toward a central position.

[0058]In yet another feature, the self steering apparatus includes a
resilient member. In a further feature of that further feature, the
resilient member includes an elastomeric element. In another further
feature, the resilient member is an elastomeric adapter pad assembly. In
another feature, the resilient member is an elastomeric adapter assembly
having a lateral force-displacement characteristic and a longitudinal
force-displacement characteristic, and the longitudinal
force-displacement characteristic is different from the lateral
force-displacement characteristic. In another feature, the elastomeric
adapter assembly is stiffer in lateral shear than in longitudinal shear.
In again another feature, a rocker element is mounted above the
elastomeric adapter pad assembly. In another feature, a rocker element is
mounted directly upon the elastomeric adapter pad assembly. In a still
further feature, the elastomeric adapter pad assembly includes and
integral rocker member. In another feature, the three piece truck is a
swing motion truck and the self steering apparatus includes an
elastomeric bearing adapter pad.

[0059]In still another feature, the wheelsets have axles, and the axles
have axes of rotation, and ends mounted beneath the sideframes, and, at
one end of one of the axles, the self steering apparatus has a force
deflection characteristic of at least one of the characteristics chosen
from the set of force-deflection characteristic consisting of:
[0060](a) linear characteristic between 3000 lbs per inch and 10,000
pounds per inch of longitudinal deflection, measured at the axis of
rotation at the end of the axle when the self steering apparatus bears
one eighth of a vertical load of between 45,000 and 70,000 lbs.;
[0061](b) linear characteristic between 16,000 lbs per inch and 60,000
pounds per inch of longitudinal deflection, measured at the axis of
rotation at the end of the axle when the self steering apparatus bears
one eighth of a vertical load of between 263,000 and 315,000 lbs.; and
[0062](c) a linear characteristic between 0.3 and 2.0 lbs per inch of
longitudinal deflection, measured at the axis of rotation at the end of
the axle per pound of vertical load passed into the one end of the one
axle.

[0063]In another aspect of the invention there is a three piece rail road
freight car truck having self steering apparatus, wherein the passive
steering apparatus includes at least one longitudinal rocker.

[0064]In an aspect of the invention, there is a three piece rail road
freight car truck having passive self steering apparatus, the self
steering apparatus having a linear force-deflection characteristic, and
the force-deflection characteristic varying as a function of vertical
loading of the truck.

[0065]In an additional feature of that aspect of the invention, the
force-displacement characteristic varies linearly with vertical loading
of the truck. In another feature, the self steering apparatus includes a
rocker mechanism. In another feature, the rocker mechanism is
displaceable from a minimum energy state under drag force applied to a
wheel of one of the wheelsets. In still another feature, the
force-deflection characteristic lies in the range of between about 0.4
lbs and 2.0 lbs per inch of deflection, measured at a center of and end
of an axle of a wheelset of the truck per pound of vertical load passed
into the end of the axle of the wheelset. In a further feature, the force
deflection characteristic lies in the range of 0.5 to 1.8 lbs per inch
per pound of vertical load passed into the end of the axle of the
wheelset.

[0066]In yet another aspect of the invention there is a three piece rail
road freight car truck having a transversely extending truck bolster, a
pair of side frames mounted at opposite ends of the truck bolster, and
resiliently connected thereto, and wheelsets. The sideframes are mounted
to the wheelsets at sideframe to wheelset interface assemblies. At least
one of the sideframe to wheelset interface assemblies is mounted between
a first end of an axle of one of the wheelsets, and a first pedestal of a
first of the sideframes. The wheelset to sideframe interface assembly
includes a first line contact rocker apparatus operable to permit lateral
swinging of the first sideframe and a second line contact rocker
apparatus operable to permit longitudinal displacement of the first end
of the axle relative to the first sideframe.

[0067]In a feature of that aspect of the invention, the first and second
rocker apparatus are mounted in series with a torsionally compliant
member, the torsionally complaint member being compliant to torsional
moments applied about a vertical axis. In another feature, a torsionally
compliant member is mounted between the first and second rocker
apparatus, the torsionally compliant member being torsionally compliant
about a vertical axis.

[0068]In a further aspect of the invention, there is a bearing adapter for
a three piece rail road freight car truck, the bearing adapter having a
rocking contact surface for rocking engagement with a mating surface of a
sideframe pedestal fitting, the rocking contact surface of the bearing
adapter having a compound curvature.

[0069]In another feature of that aspect of the invention, the compound
curvature is formed on a first male radius of curvature and a second male
radius of curvature oriented cross-wise thereto. In another feature, the
compound curvature is saddle shaped. In a further feature, the compound
curvature is ellipsoidal. In a further feature, the curvature is
spherical.

[0070]In a still further aspect there is a railroad car truck having a
laterally extending truck bolster. The truck bolster has first and second
ends. First and second longitudinally extending sideframes are
resiliently mounted at the first and second ends of the bolster
respectively. The side frames are mounted on wheelsets at sideframe to
wheelset mounting interface assemblies. A four cornered damper group is
mounted between each end of the truck bolster and the respective side
frame to which that end is mounted. The sideframe to wheelset mounting
interface assemblies are torsionally compliant about a vertical axis.

[0071]In a feature of that aspect of the invention, the truck is free of
unsprung lateral cross-members between the sideframes. In another
feature, the sideframes are mounted to swing laterally. In still another
feature, the sideframe to wheelset mounting interface assemblies include
self steering apparatus.

[0072]In another aspect of the invention, there is a railroad freight car
truck having wheelsets mounted in a pair of sideframes, the sideframes
having sideframe pedestals for receiving the wheelsets. The sideframe
pedestals have sideframe pedestal jaws. The sideframe pedestal jaws
include sideframe pedestal jaw thrust blocks. The wheelsets have bearing
adapters mounted thereto for installation between the jaws. The sideframe
pedestals have respective pedestal seat members rockingly co-operable
with the bearing adapter. The truck has members mounted intermediate the
jaws and the bearing adapters for urging the bearing adapter to a
centered position relative to the pedestal seat. In another aspect, there
is a member for placement between the thrust lug of a railroad car
sideframe pedestal jaw and the end wall and corner abutments of a bearing
adapter, the member being operable to urge the bearing adapter to an at
rest position relative to the sideframe.

[0073]In another aspect of the invention there is a sideframe pedestal to
axle bearing interface assembly for a three piece rail road car truck.
The interface assembly has fittings operable to rock both laterally and
longitudinally, and the interface assembly includes a bearing assembly
having one of the rocking surface fittings defined integrally thereon.

[0074]In an additional feature of that aspect of the invention the bearing
assembly includes a rocking surface of compound curvature. In another
feature, the fittings include rockingly matable saddle surfaces. In yet
another feature, the fittings include a male surface having a first
compound curvature and a mating female surface having a second compound
curvature in rocking engagement with each other. One of the surfaces
includes a spherical portion. In still another feature, relative to a
vertical axis of rotation, rocking motion of the fittings longitudinally
is torsionally de-coupled from rocking of the fittings laterally. In
still yet another feature, the fittings include a force transfer
interface that is torsionally compliant relative to torsional moments
about a vertical axis. In a further feature, the assembly includes a
resilient biasing member.

[0075]In an aspect of the invention there is a sideframe pedestal to axle
bearing interface assembly for a three piece rail road car truck. The
interface assembly has fittings operable to rock both laterally and
longitudinally, and the interface assembly includes a bearing assembly
having one of the rocking surface fittings defined integrally thereon.

[0076]In an additional feature of that aspect of the invention, the
bearing assembly includes a rocking surface of compound curvature. In
another feature, the fittings include rockingly matable saddle surfaces.
In still another feature, the fittings include a male surface having a
first compound curvature and a mating female surface having a second
compound curvature in rocking engagement with each other, and one of the
surfaces includes at least a spherical portion. In yet another feature,
relative to a vertical axis of rotation, rocking motion of the fittings
longitudinally is torsionally de-coupled from rocking of the fittings
laterally. In still yet another feature, the fittings include a force
transfer interface that is torsionally compliant relative to torsional
moments about a vertical axis. In a further feature, the assembly
includes a resilient biasing member.

[0077]In another aspect of the invention, there is a sideframe pedestal to
axle bearing interface assembly for a three piece rail road car truck.
The interface assembly has mating rocking surfaces. The assembly includes
a bearing mounted to an end of a wheelset axle. The bearing has an outer
ring, and one of the rocking surfaces is rigidly fixed relative to the
bearing.

[0078]In still another aspect of the invention, there is a bearing for
mounting to one end of an axle of a wheelset of a three-piece railroad
car truck. The bearing has an outer member mounted in a position to
permit the end of the axle to rotate relative thereto, and the outer
member has a rocking surface formed thereon for engaging a mating rolling
contact surface of a pedestal seat member of a sideframe of the three
piece truck. In an additional feature of that aspect of the invention,
the bearing has an axis of rotation coincident with a centerline axis of
the axle and the surface has a region of minimum radial distance from the
center of rotation and a positive derivative dr/dθ between the
region and points angularly adjacent thereto on either side.

[0079]In another feature, the surface is cylindrical. In yet another
feature, the surface has a constant radius of curvature. In still another
feature, the cylinder has an axis parallel to the axis of rotation of the
bearing. In still yet another feature, when installed in the three piece
truck, the surface has a local minimum potential energy position, the
position of minimum potential energy being located between positions of
greater potential energy. In yet another feature, the surface is a
surface of compound curvature. In still yet another feature, the surface
has the form of a saddle. In a further feature, the surface has a radius
of curvature. The bearing has an axis of rotation, and a region of
minimum radial distance from the axis of rotation. The radius of
curvature is greater than the minimum radial distance.

[0080]In yet a further feature, there is a combination of a bearing and a
pedestal seat. In an additional feature, the bearing has an axis of
rotation. A first location on the surface of the bearing lies radially
closer to the axis of rotation than any other location thereon; a first
distance, L is defined between the axis of rotation and the first
location. The surface of the bearing and the surface of the pedestal seat
each have a radius of curvature and mate in a male and female
relationship. One radius of curvature is a male radius of curvature
r1. The other radius of curvature is a female radius of curvature,
R2; r1 being greater than L, R2 is greater than r1,
and L, r1 and R2 conform to the formula
L-1-(r1-1-R2-1)>0. In another additional
feature, the rocking surfaces are co-operable to permit self steering.

[0081]In still another aspect of the invention there is a three-piece
railroad freight car truck. It has a bolster sprung between sideframes.
The bolster is mounted to permit limited lateral travel thereof relative
to the sideframes. The bolster has a first range of lateral travel
relative to the sideframes when loaded under a first magnitude of
vertical load, and a second, different, range of lateral travel relative
to the sideframes under a second, different magnitude of vertical load.

[0082]In another feature, of that aspect of the invention, the second
magnitude of vertical load is greater than the first magnitude, and the
second range of lateral travel is greater than the first range. In a
further feature, the bolster has the first range of travel in a light car
condition, and the second range of travel in a fully laden car condition,
the second range of travel being greater than the first range of travel.
In yet another feature, the range of travel varies as a function of
vertical loading of the bolster. In still another feature, the range of
travel varies linearly as a function of vertical loading of the bolster.
In a yet further feature, the range of travel increases linearly as a
function of increasing vertical load on the bolster. In another feature,
the first range permits lateral motion to either side of an at rest
position through a maximum amplitude, and the maximum amplitude is in the
range of 3/8 to 3/4 of an inch. In another feature, the second range
permits lateral motion to either side of an at rest position through a
maximum amplitude, and the maximum amplitude is in the range of 7/8 to
13/8 inches. In a still further feature, the bolster has a first end
resiliently mounted to a first of the sideframes and a second end
resiliently mounted to a second of the sideframes, and dampers are
mounted in four-cornered groups to act between each of the bolsters ends
and the sideframes respectively. In another feature, the dampers have
non-metallic friction surfaces. In another feature, the truck is
self-steering. In another feature, the truck has sideframe to wheelset
interface fittings permitting lateral swinging motion thereof. In yet
another further feature, the truck has respective four cornered,
non-stick-slip groups of dampers acting between the bolster and each of
the sideframes, the truck has sideframe to wheelset interface fittings
permitting lateral swinging motion thereof, and the truck is a
self-steering truck. In another feature, the truck has dampers acting
between the bolster and each of the sideframes, and one of the dampers
has a damper body and a friction member mounted to the damper body, the
friction member being operably mounted to bear against a co-operating
wear plate during displacement of the bolster relative to one of the
sideframes, and the friction member has a mounting permitting angular
displacement of the friction member about at least two axes of rotation
relative to the damper body while the friction member remains in
engagement with the wear plate.

[0083]In still another aspect of the invention, there is a railroad
freight car truck having a bolster sprung between sideframes, the bolster
being mounted to permit lateral travel thereof relative to the
sideframes, the bolster having a range of lateral travel whose magnitude
is a function of vertical displacement of the bolster. In another feature
of that aspect of the invention, the range of travel is a linear function
of vertical displacement of the bolster. In still another feature, the
range of lateral travel of the bolster increases with increasing downward
vertical displacement of the bolster relative to the sideframes. In yet
another feature, the range of lateral travel of the bolster is a linear
function of downward displacement of the bolster, wherein the range of
lateral travel of the bolster increases in a range of proportion of
between 3/16 inches and 5/16 inches of additional lateral travel for
every 1 inch of additional downward deflection of the bolster at rest.

[0084]In another aspect of the invention, there is a three piece rail road
car truck. It has sideframes mounted to a pair of wheelsets, and a
bolster extending cross-wise between the sideframes. The bolster has
first and second ends each resiliently mounted to a respective one of the
sideframes. The bolster has gibs. The sideframes have stops positioned to
oppose the gibs. Mating pairs of respective ones of the gibs and the
stops are co-operatively engageable to limit transverse displacement of
the bolster relative to the sideframes. The bolster has a first at rest
position relative to the sideframes under a first vertical loading
condition, and a second at rest position relative to the sideframes under
a second, different, vertical loading condition. In the first at rest
position of the bolster there being a first gap distance between a first
bolster gib and its paired stop. In the second at rest position of the
bolster there is a second, different, gap distance between that same
first bolster gib and its paired stop.

[0085]In another feature of that aspect of the invention, the sideframes
are mounted to the wheelsets at respective sideframe to wheelset
interface fittings, and those fittings include rocker members permitting
the sideframes to swing laterally. In another feature, the truck has a
four cornered arrangement of dampers mounted to act between each of the
sideframes and a respective one of the ends of the bolster. In another
feature, the first bolster gib has an abutment surface for mating its
paired stop, and the abutment surface is not confined to a vertical
plane. In another feature, the bolster gib has an abutment surface for
mating with its paired stop, the abutment surface being inclined with
respect to vertical. In another feature, the paired stop of the first
bolster gib has an abutment surface for engaging the first bolster gib,
and the abutment surface is not confined to a vertical plane. In another
feature, the paired stop of the first bolster gib has an abutment surface
for engaging the first bolster gib, and the abutment surface is inclined
with respect to vertical. In another feature, the first bolster gib and
its paired stop having mating abutment surfaces for limiting lateral
travel of the bolster, the mating abutment surfaces being inclined with
respect to vertical. In another feature, the outboard bolster gib is
inclined with respect to vertical. In another feature, both the inboard
bolster gib and the outboard bolster gib are tapered with respect to
vertical.

[0086]In still another aspect of the invention, there is a damper assembly
for installation between a truck bolster and a sideframe of a three piece
railroad car truck. The damper assembly has a damper body and a friction
member mountable to the damper body, the damper body is seatable in a
bolster pocket and is engageable by a damper biasing member. The friction
member having a friction surface for engagement with a wear plate; and
the friction member having at least two rotational degrees of freedom
relative to the damper body when mounted thereto.

[0087]In another feature of that aspect of the invention, the damper body
and the friction member have mutually engaging arcuate surfaces, those
surfaces being formed on a body of revolution. In another feature, the
damper body and the friction member have mutually engaging arcuate
surfaces, those surfaces being formed on a spherical arc. In another
feature, the mutually engaging surfaced are in a non-rocking
relationship. In another feature, the surfaces are mounted in a sliding
relationship. In another feature, the body includes members for engaging
a biasing member. In another feature, the body includes a sloped face for
seating against an inclined face of a damper pocket, and the slope face
is free of a crown. In another feature, the friction member includes a
first portion for engagement with the damper body, and a second portion
for engagement with a wear plate, and the second portion is made from a
different material than the first portion. In another feature, the
surface of the friction member is formed on a bulging portion thereof,
and the damper body includes a cavity for accommodating the bulging
portion of the friction member. In another feature, the friction surface
has a circular footprint.

[0088]These and other aspects and features of the invention may be
understood with reference to the detailed descriptions of the invention
and the accompanying illustrations as set forth below.

BRIEF DESCRIPTION OF THE FIGURES

[0089]The principles of the invention may better be understood with
reference to the accompanying figures provided by way of illustration of
an exemplary embodiment, or embodiments, incorporating principles and
aspects of the present invention, and in which:

[0090]FIG. 1a shows an isometric view of an example of an embodiment of a
railroad car truck;

[0091]FIG. 1b shows a top view of the railroad car truck of FIG. 1a;

[0092]FIG. 1c shows a side view of the railroad car truck of FIG. 1a;

[0093]FIG. 1d shows an exploded view of a portion of a truck similar to
that of FIG. 1a;

[0094]FIG. 1e is an exploded, sectioned view of an example of an alternate
three piece truck to that of FIG. 1a, having dampers mounted along the
spring group centerlines;

[0095]FIG. 1f shows an isometric view of an example of an alternate
railroad car truck according to that of FIG. 1a;

[0096]FIG. 1g shows a side view of the railroad car truck of FIG. 1f;

[0097]FIG. 1h shows a top view of the railroad car truck of FIG. 1f;

[0098]FIG. 1i is a split view showing, in one half an end view of the
truck of FIG. 1f, and in the other half and a section taken level with
the truck center;

[0099]FIG. 1j shows a spring layout for the truck of FIG. 1f;

[0100]FIG. 2a is an enlarged detail of a side view of a truck such as the
truck of FIG. 1a, 1b, 1c or 1e taken at the sideframe pedestal to bearing
adapter interface;

[0101]FIG. 2b shows a lateral cross-section through the sideframe pedestal
to bearing interface of FIG. 2a, taken at the wheelset axle centerline;

[0102]FIG. 2c shows the cross-section of FIG. 2b in a laterally deflected
condition;

[0103]FIG. 2d is a longitudinal section of the pedestal seat to bearing
adapter interface of FIG. 2a, on the longitudinal plane of symmetry of
the bearing adapter;

[0135]FIG. 9a shows an exploded isometric view of an alternate assembly to
that of FIG. 3a;

[0136]FIG. 9b shows an exploded isometric view similar to the view of FIG.
9a, showing a bearing adapter assembly incorporating an elastomeric pad;

[0137]FIG. 10a shows an exploded isometric view of an alternate assembly
to that of FIG. 3a;

[0138]FIG. 10b shows a perspective view of a bearing adapter of the
assembly of FIG. 10a from above and to one corner;

[0139]FIG. 10c shows a perspective of the bearing adapter of FIG. 10b from
below;

[0140]FIG. 10d shows a bottom view of the bearing adapter of FIG. 10b;

[0141]FIG. 10e shows a longitudinal section of the bearing adapter of FIG.
10b taken on section `10e-10e` of FIG. 10d; and

[0142]FIG. 10f shows a transverse section of the bearing adapter of FIG.
10b taken on section `10f-10f` of FIG. 10d;

[0143]FIG. 11a is an exploded view of an alternate bearing adapter
assembly to that of FIG. 3a;

[0144]FIG. 11b shows a view of the bearing adapter of FIG. 11a from below
and to one corner;

[0145]FIG. 11c is a top view of the bearing adapter of FIG. 11b;

[0146]FIG. 11d is a lengthwise section of the bearing adapter of FIG. 11c
on `11d-11d`;

[0147]FIG. 11e is a cross-wise section of the bearing adapter of FIG. 11c
on `11e-11e`; and

[0148]FIG. 11f is a set of views of a resilient pad member of the assembly
of FIG. 11a;

[0149]FIG. 11g shows a view of the bearing adapter of FIG. 11a from above
and to one corner;

[0150]FIG. 12a shows an exploded isometric view of an alternate bearing
adapter to pedestal seat assembly to that of FIG. 3a;

[0151]FIG. 12b shows a longitudinal central section of the assembly of
FIG. 12a, as assembled;

[0152]FIG. 12c shows a section on `12c-12c` of FIG. 12b; and

[0153]FIG. 12d shows a section on `12d-12d` of FIG. 12b;

[0154]FIG. 13a shows a top view of an embodiment of bearing adapter and
pedestal seat such as could be used in a side frame pedestal similar to
that of FIG. 2a, with the seat inverted to reveal a female depression
formed therein for engagement with the bearing adapter;

[0155]FIG. 13b shows a side view of the bearing adapter and seat of FIG.
13a;

[0156]FIG. 13c shows a longitudinal section of the bearing adapter of FIG.
13a taken on section `13c-13c` of FIG. 13d;

[0157]FIG. 13d shows an end view of the bearing adapter and pedestal seat
of FIG. 13a;

[0158]FIG. 13e shows a transverse section of the bearing adapter of FIG.
13a, taken on the wheelset axle centerline;

[0159]FIG. 13f is a section in the transverse plane of symmetry of a
bearing adapter and pedestal seat pair like that of FIG. 13e, with
inverted rocker and seat portions;

[0160]FIG. 13g shows a cross-section on the longitudinal plane of symmetry
of the bearing adapter and pedestal seat pair of FIG. 13f;

[0161]FIG. 14a shows an isometric view of an alternate embodiment of
bearing adapter and pedestal seat to that of FIG. 13a having a fully
curved upper surface;

[0162]FIG. 14b shows a side view of the bearing adapter and seat of FIG.
14a;

[0163]FIG. 14c shows an end view of the bearing adapter and seat of FIG.
14a;

[0164]FIG. 14d shows a cross-section of the bearing adapter and pedestal
seat of FIG. 14a taken on the longitudinal plane of symmetry;

[0165]FIG. 14e shows a cross-section of the bearing adapter and pedestal
seat of FIG. 14a taken on the transverse plane of symmetry;

[0166]FIG. 15a shows a top view of an alternate bearing adapter and an
inverted view of an alternate female pedestal seat to that of FIG. 13a;

[0167]FIG. 15b shows a longitudinal section of the bearing adapter of FIG.
15a;

[0168]FIG. 15c shows an end view of the bearing adapter and seat of FIG.
15a;

[0169]FIG. 16a shows an isometric view of a further embodiment of bearing
adapter and seat combination to that of FIG. 13a, in which the bearing
adapter and pedestal seat have saddle shaped engagement interfaces;

[0170]FIG. 16b shows an end view of the bearing adapter and pedestal seat
of FIG. 16a;

[0171]FIG. 16c shows a side view of the bearing adapter and pedestal seat
of FIG. 16a;

[0172]FIG. 16d is a lateral section of the adapter and pedestal seat of
FIG. 16a;

[0173]FIG. 16e is a longitudinal section of the adapter and pedestal seat
of FIG. 16a;

[0174]FIG. 16f shows a transverse cross section of a bearing adapter and
pedestal seat pair having an inverted interface to that of FIG. 16a;

[0176]FIG. 17a shows an exploded side view of a further alternate bearing
adapter and seat combination to that of FIG. 13a, having a pair of
cylindrical rocker elements, and a pivoted connection therebetween;

[0177]FIG. 17b shows an exploded end view of the bearing adapter and seat
of FIG. 17a;

[0178]FIG. 17c shows a cross-section of the bearing adapter and seat of
FIG. 17a, as assembled, taken on the longitudinal centerline thereof;

[0179]FIG. 17d shows a cross-section of the bearing adapter and seat of
FIG. 17a, as assembled, taken on the transverse centerline thereof;

[0189]FIG. 20a is a view of a bearing adapter for use in the assembly of
FIG. 19a;

[0190]FIG. 20b shows a top view of the bearing adapter of FIG. 20a;

[0191]FIG. 20c shows a longitudinal cross-section of the bearing adapter
of FIG. 20a;

[0192]FIG. 21a shows an isometric view of a pad adapter for the assembly
of FIG. 19a;

[0193]FIG. 21b shows a top view of the pad adapter of FIG. 21a;

[0194]FIG. 21c shows a side view of the pad adapter of FIG. 21a;

[0195]FIG. 21d shows a half cross-section of the pad adapter of FIG. 21a;

[0196]FIG. 21e shows an isometric view of a rocker for the pad adapter of
FIG. 21a;

[0197]FIG. 21f shows a top view of the rocker of FIG. 21a;

[0198]FIG. 21g shows an end view of the rocker of FIG. 21a;

[0199]FIG. 22a shows an end view of an alternate arrangement of wheelset
to pedestal interface assembly arrangement to that of FIG. 2a, having
mating bi-directionally arcuate rocking members, one being formed
integrally as an outer portion of a bearing;

[0200]FIG. 22b shows a cross-section of the assembly of FIG. 22a taken on
`22b-22b` of FIG. 22a;

[0201]FIG. 22c shows a cross-section of the assembly of FIG. 22a as viewed
in the direction of arrows `22c-22c` of FIG. 22b;

[0202]FIG. 23a shows an end view of an alternate assembly to that of FIG.
22a incorporating a uni-directionally fore-and-aft rocking member;

[0203]FIG. 23b shows a cross-sectional view taken on `23b-23b` of FIG.
23a;

[0204]FIG. 24a shows an isometric view of an alternate three piece truck
to that of FIG. 1a;

[0205]FIG. 24b shows a side view of the three piece truck of FIG. 24a;

[0206]FIG. 24c shows a top view of half of the three piece truck of FIG.
24b;

[0207]FIG. 24d shows a partial section of the truck of FIG. 24b taken on
`24d-24d`;

[0208]FIG. 24e shows a partial isometric view of the truck bolster of the
three piece truck of FIG. 24a showing friction damper seats;

[0209]FIG. 24f shows a force schematic for four cornered damper
arrangements generally, such as, for example, in the trucks of FIGS. 1a,
1f, and FIG. 24a;

[0210]FIG. 25a shows a side view of an alternate three piece truck to that
of FIG. 24a;

[0211]FIG. 25b shows a top view of half of the three piece truck of FIG.
25a;

[0212]FIG. 25c shows a partial section of the truck of FIG. 25a taken on
`25c-25c`;

[0213]FIG. 25d shows an exploded isometric view of the bolster and side
frame assembly of FIG. 25a, in which horizontally acting springs drive
constant force dampers;

[0214]FIG. 26a shows an alternate version of the bolster of FIG. 24e, with
a double sized damper pocket for seating a large single wedge having a
welded insert;

[0215]FIG. 26b shows an alternate dual wedge for a truck bolster like that
of FIG. 26a;

[0216]FIG. 27a shows an alternate bolster arrangement similar to that of
FIG. 5, but having split wedges;

[0217]FIG. 27b shows a bolster similar to that of FIG. 24a, having a wedge
pocket having primary and secondary angles and a split wedge arrangement
for use therewith;

[0218]FIG. 27c shows an alternate stepped single wedge for the bolster of
FIG. 27b;

[0219]FIG. 28a shows an alternate bolster and wedge arrangement to that of
FIG. 17b, having secondary wedge angles;

[0232]FIG. 30f shows a bottom view of the damper assembly of FIG. 30a; and

[0233]FIG. 30g shows a mid-sectional view on a vertical plane `30g-30g` of
the damper assembly of FIG. 30e.

DETAILED DESCRIPTION OF THE INVENTION

[0234]The description that follows, and the embodiments described therein,
are provided by way of illustration of an example, or examples, of
particular embodiments of the principles of aspects of the present
invention. These examples are provided for the purposes of explanation,
and not of limitation, of those principles and of the invention. In the
description, like parts are marked throughout the specification and the
drawings with the same respective reference numerals. The drawings are
not necessarily to scale and in some instances proportions may have been
exaggerated in order more clearly to depict certain features of the
invention.

[0235]In terms of general orientation and directional nomenclature, for
each of the rail road car trucks described herein, the longitudinal
direction is defined as being coincident with the rolling direction of
the rail road car, or rail road car unit, when located on tangent (that
is, straight) track. In the case of a rail road car having a center sill,
the longitudinal direction is parallel to the center sill, and parallel
to the side sills, if any. Unless otherwise noted, vertical, or upward
and downward, are terms that use top of rail, TOR, as a datum. The term
lateral, or laterally outboard, refers to a distance or orientation
relative to the longitudinal centerline of the railroad car, or car unit.
The term "longitudinally inboard", or "longitudinally outboard" is a
distance taken relative to a mid-span lateral section of the car, or car
unit. Pitching motion is angular motion of a railcar unit about a
horizontal axis perpendicular to the longitudinal direction. Yawing is
angular motion about a vertical axis. Roll is angular motion about the
longitudinal axis.

[0236]This description relates to rail car trucks and truck components.
Several AAR standard truck sizes are listed at page 711 in the 1997 Car &
Locomotive Cyclopedia. As indicated, for a single unit rail car having
two trucks, a "40 Ton" truck rating corresponds to a maximum gross car
weight on rail (GRL) of 142,000 lbs. Similarly, "50 Ton" corresponds to
177,000 lbs., "70 Ton" corresponds to 220,000 lbs., "100 Ton" corresponds
to 263,000 lbs., and "125 Ton" corresponds to 315,000 lbs. In each case
the load limit per truck is then half the maximum gross car weight on
rail. Two other types of truck are the "110 Ton" truck for railcars
having a 286,000 lbs. GRL and the "70 Ton Special" low profile truck
sometimes used for auto rack cars. Given that the rail road car trucks
described herein tend to have both longitudinal and transverse axes of
symmetry, a description of one half of an assembly may generally also be
intended to describe the other half as well, allowing for differences
between right hand and left hand parts.

[0237]This description refers to friction dampers for rail road car
trucks, and multiple friction damper systems. There are several types of
damper arrangements, some being shown at pp. 715-716 of the 1997 Car and
Locomotive Cyclopedia, those pages being incorporated herein by
reference. Each of the arrangements of dampers shown at pp. 715 to 716 of
the 1997 Car and Locomotive Cyclopedia can be modified to employ a four
cornered, double damper arrangement of inner and outer dampers.

[0238]In terms of general nomenclature, damper wedges tend to be mounted
within an angled "bolster pocket" formed in an end of the truck bolster.
In cross-section, each wedge may then have a generally triangular shape,
one side of the triangle being, or having, a bearing face, a second side
which might be termed the bottom, or base, forming a spring seat, and the
third side being a sloped side or hypotenuse between the other two sides.
The first side may tend to have a substantially planar bearing face for
vertical sliding engagement against an opposed bearing face of one of the
sideframe columns. The second face may not be a face, as such, but rather
may have the form of a socket for receiving the upper end of one of the
springs of a spring group. Although the third face, or hypotenuse, may
appear to be generally planar, it may tend to have a slight crown, having
a radius of curvature of perhaps 60''. The crown may extend along the
slope and may also extend across the slope. The end faces of the wedges
may be generally flat, and may have a coating, surface treatment, shim,
or low friction pad to give a smooth sliding engagement with the sides of
the bolster pocket, or with the adjacent side of another independently
slidable damper wedge, as may be.

[0239]During railcar operation, the sideframe may tend to rotate, or
pivot, through a small range of angular deflection about the end of the
truck bolster to yield wheel load equalization. The slight crown on the
slope face of the damper may tend to accommodate this pivoting motion by
allowing the damper to rock somewhat relative to the generally inclined
face of the bolster pocket while the planar bearing face remains in
planar contact with the wear plate of the sideframe column. Although the
slope face may have a slight crown, for the purposes of this description
it will be described as the slope face or as the hypotenuse, and will be
considered to be a substantially flat face as a general approximation.

[0240]In the terminology herein, wedges have a primary angle α,
being the included angle between (a) the sloped damper pocket face
mounted to the truck bolster, and (b) the side frame column face, as seen
looking from the end of the bolster toward the truck center. In some
embodiments, a secondary angle may be defined in the plane of angle
α, namely a plane perpendicular to the vertical longitudinal plane
of the (undeflected) side frame, tilted from the vertical at the primary
angle. That is, this plane is parallel to the (undeflected) long axis of
the truck bolster, and taken as if sighting along the back side
(hypotenuse) of the damper. The secondary angle β is defined as the
lateral rake angle seen when looking at the damper parallel to the plane
of angle α. As the suspension works in response to track
perturbations, the wedge forces acting on the secondary angle β may
tend to urge the damper either inboard or outboard according to the angle
chosen.

[0241]General Description of Truck Features

[0242]FIGS. 1a and 1f provide examples of trucks 20 and 22 may have the
same, or generally similar, features and similar construction, although
they may differ in pendulum length, spring stiffness, wheelbase, window
width and height, and damping arrangement. That is, truck 20 of FIG. 1f
may tend to have a longer wheelbase (from 73 inches to 86 inches,
possibly between 80-84 inches for truck 20, as opposed to a wheelbase of
63-73 inches for truck 22), may tend to have a main spring group having a
softer vertical spring rate, and a four cornered damper group that may
have different primary and secondary angles on the damper wedges. Truck
20 may have a 5×3 spring group arrangement, while truck 22 may have
a 3×3 arrangement. While either truck may be suitable for a variety
of general purpose uses, truck 20 may be optimized for carrying
relatively low density, high value lading, such as automobiles or
consumer products, for example, whereas truck 22 may be optimized for
carrying denser semi-finished industrial goods, such as might be carried
in rail road freight cars for transporting rolls of paper. The various
features of the two truck types may be interchanged, and are intended to
be illustrative of a wide range of truck types. Notwithstanding possible
differences in size, generally similar features are given the same part
numbers. Trucks 20 and 22 are symmetrical about both their longitudinal
and transverse, or lateral, centerline axes. In each case, where
reference is made to a sideframe, it will be understood that the truck
has first and second sideframes, first and second spring groups, and so
on.

[0243]Trucks 20 and 22 each have a truck bolster 24 and sideframes 26.
Each sideframe 26 has a generally rectangular window 28 that accommodates
one of the ends 30 of the bolster 24. The upper boundary of window 28 is
defined by the sideframe arch, or compression member identified as top
chord member 32, and the bottom of window 28 is defined by a tension
member identified as bottom chord 34. The fore and aft vertical sides of
window 28 are defined by sideframe columns 36. The ends of the tension
member sweep up to meet the compression member. At each of the swept-up
ends of sideframe 26 there are sideframe pedestal fittings, or pedestal
seats 38. Each fitting 38 accommodates an upper fitting, which may be a
rocker or a seat, as described and discussed below. This upper fitting,
whichever it may be, is indicated generically as 40. Fitting 40 engages a
mating fitting 42 of the upper surface of a bearing adapter 44. Bearing
adapter 44 engages a bearing 46 mounted on one of the ends of one of the
axles 48 of the truck adjacent one of the wheels 50. A fitting 40 is
located in each of the fore and aft pedestal fittings 38, the fittings 40
being longitudinally aligned so the sideframe can swing sideways relative
to the truck's rolling direction.

[0244]The relationship of the mating fittings 40 and 42 is described at
greater length below. The relationship of these fittings determines part
of the overall relationship between an end of one of the axles of one of
the wheelsets and the sideframe pedestal. That is, in determining the
overall response, the degrees of freedom of the mounting of the axle end
in the sideframe pedestal involve a dynamic interface across an assembly
of parts, such as may be termed a wheelset to sideframe interface
assembly, that may include the bearing, the bearing adapter, an
elastomeric pad, if used, a rocker if used, and the pedestal seat mounted
in the roof of the sideframe pedestal. Several different embodiments of
this wheelset to sideframe interface assembly are described below. To the
extent that bearing 46 has a single degree of freedom, namely rotation
about the wheelshaft axis, analysis of the assembly can be focused on the
bearing to pedestal seat interface assembly, or on the bearing adapter to
pedestal seat interface assembly. For the purposes of this description,
items 40 and 42 are intended generically to represent the combination of
features of a bearing adapter and pedestal seat assembly defining the
interface between the roof of the sideframe pedestal and the bearing
adapter, and the six degrees of freedom of motion at that interface,
namely vertical, longitudinal and transverse translation (i.e.,
translation in the z, x, and y directions) and pitching, rolling, and
yawing (i.e., rotational motion about the y, x, and z axes respectively)
in response to dynamic inputs.

[0245]The bottom chord or tension member of sideframe 26 may have a basket
plate, or lower spring seat 52 rigidly mounted thereto. Although trucks
20 and 22 may be free of unsprung lateral cross-bracing, whether in the
nature of a transom or lateral rods, in the event that truck 20 or 22 is
taken to represent a "swing motion" truck with a transom or other cross
bracing, the lower rocker platform of spring seat 52 may be mounted on a
rocker, to permit lateral rocking relative to sideframe 26. Spring seat
52 may have retainers for engaging the springs 54 of a spring set, or
spring group, 56, whether internal bosses, or a peripheral lip for
discouraging the escape of the bottom ends of the springs. The spring
group, or spring set 56, is captured between the distal end 30 of bolster
24 and spring seat 52, being placed under compression by the weight of
the rail car body and lading that bears upon bolster 24 from above.

[0246]Bolster 24 has double, inboard and outboard, bolster pockets 60, 62
on each face of the bolster at the outboard end (i.e., for a total of 8
bolster pockets per bolster, 4 at each end). Bolster pockets 60, 62
accommodate fore and aft pairs of first and second, laterally inboard and
laterally outboard friction damper wedges 64, 66 and 68, 70,
respectively. Each bolster pocket 60, 62 has an inclined face, or damper
seat 72, that mates with a similarly inclined hypotenuse face 74 of the
damper wedge, 64, 66, 68 and 70. Wedges 64, 66 each sit over a first,
inboard corner spring 76, 78, and wedges 68, 70 each sit over a second,
outboard corner spring 80, 82. Angled faces 74 of wedges 64, 66 and 68,
70 ride against the angled faces of respective seats 72.

[0247]A middle end spring 96 bears on the underside of a land 98 located
intermediate bolster pockets 60 and 62. The top ends of the central row
of springs, 100, seat under the main central portion 102 of the end of
bolster 24. In this four corner arrangement, each damper is individually
sprung by one or another of the springs in the spring group. The static
compression of the springs under the weight of the car body and lading
tends to act as a spring loading to bias the damper to act along the
slope of the bolster pocket to force the friction surface against the
sideframe. Friction damping is provided when the vertical sliding faces
90 of the friction damper wedges 64, 66 and 68, 70 ride up and down on
friction wear plates 92 mounted to the inwardly facing surfaces of
sideframe columns 36. In this way the kinetic energy of the motion is, in
some measure, converted through friction to heat. This friction may tend
to damp out the motion of the bolster relative to the sideframes. When a
lateral perturbation is passed to wheels 50 by the rails, rigid axles 48
may tend to cause both sideframes 26 to deflect in the same direction.
The reaction of sideframes 26 is to swing, like pendula, on the upper
rockers. The weight of the pendulum and the reactive force arising from
the twisting of the springs may then tend to urge the sideframes back to
their initial position. The tendency to oscillate harmonically due to
track perturbations may tend to be damped out by the friction of the
dampers on the wear plates 92.

[0248]As compared to a bolster with single dampers, such as may be mounted
on the sideframe centerline as shown in FIG. 1e, for example, the use of
doubled dampers such as spaced apart pairs of dampers 64, 68 may tend to
give a larger moment arm, as indicated by dimension "2M" in FIG. 1d, for
resisting parallelogram deformation of truck 22 more generally. Use of
doubled dampers may yield a greater restorative "squaring" force to
return the truck to a square orientation than for a single damper alone
with the restorative bias, namely the squaring force, increasing with
increasing deflection. That is, in parallelogram deformation, or
lozenging, the differential compression of one diagonal pair of springs
(e.g., inboard spring 76 and outboard spring 82 may be more pronouncedly
compressed) relative to the other diagonal pair of springs (e.g., inboard
spring 78 and outboard spring 80 may be less pronouncedly compressed than
springs 76 and 82) tends to yield a restorative moment couple acting on
the sideframe wear plates. This moment couple tends to rotate the
sideframe in a direction to square the truck, (that is, in a position in
which the bolster is perpendicular, or "square", to the sideframes). As
such, the truck is able to flex, and when it flexes the dampers
co-operate in acting as biased members working between the bolster and
the side frames to resist parallelogram, or lozenging, deformation of the
side frame relative to the truck bolster and to urge the truck back to
the non-deflected position.

[0249]The foregoing explanation has been given in the context of trucks 20
and 22, each of which has a spring group that has three rows facing the
sideframe columns. The restorative moment couple of a four-cornered
damper layout can also be explained in the context of a truck having a 2
row spring group arrangement facing the dampers, as in truck 400 of FIGS.
14a to 14e. For the purposes of conceptual visualization, the normal
force on the friction face of any of the dampers can be taken as a
pressure field whose effect can be approximated by a point load acting at
the centroid of the pressure field and whose magnitude is equal to the
integrated value of the pressure field over its area. The center of this
distributed force, acting on the inboard friction face of wedge 440
against column 428 can be thought of as a point load offset transversely
relative to the diagonally outboard friction face of wedge 443 against
column 430 by a distance that is nominally twice dimension 1' shown in
the conceptual sketch of FIG. 1k. In the example of FIG. 14a, this
distance, 2L, is about one full diameter of the large spring coils in the
spring set. The restoring moment in such a case would be, conceptually,
MR=[(F1+F3)-(F2+F4)]L. This may be expressed
MR=4kc Tan(ε) Tan(θ)L, where θ is the
primary angle of the damper (generally illustrated as α herein),
and kc is the vertical spring constant of the coil upon which the
damper sits and is biased.

[0250]In the various arrangements of spring groups 2×4, 3×3,
3:2:3 or 3×5 group, dampers may be mounted over each of four corner
positions. The portion of spring force acting under the damper wedges may
be in the 25-50% range for springs of equal stiffness. If not of equal
stiffness, the portion of spring force acting under the dampers may be in
the range of perhaps 20% to 35%. The coil groups can be of unequal
stiffness if inner coils are used in some springs and not in others, or
if springs of differing spring constant are used.

[0251]An enhanced tendency to encourage squareness at the bolster to
sideframe interface (i.e., through the use of four cornered damper
groups) may tend to reduce reliance on squareness at the pedestal to
wheelset axle interface, and turn, may tend to provide an opportunity to
employ a torsionally compliant (about the vertical axis) axle to pedestal
interface assembly, and to permit a measure of self steering.

[0252]The bearing plate, namely wear plate 92 (FIG. 1a) is significantly
wider than the through thickness of the sideframes more generally, as
measured, for example, at the pedestals, and may tend to be wider than
has been conventionally common. This additional width corresponds to the
additional overall damper span width measured fully across the damper
pairs, plus lateral travel as noted above, typically allowing 11/2 (+/-)
inches of lateral travel of the bolster relative to the sideframe to
either side of the undeflected central position. That is, rather than
having the width of one coil, plus allowance for travel, plate 92 may
have the width of three coils, plus allowance to accommodate 11/2 (+/-)
inches of travel to either side for a total, double amplitude travel of
3'' (+/-). Bolster 24 has inboard and outboard gibs 106, 108
respectively, that bound the lateral motion of bolster 24 relative to
sideframe columns 36. This motion allowance may be in the range of
+/-11/8 to 13/4 in., and may be in the range of 1 3/16 to 1 9/16 in., and
can be set, for example, at 11/2 in. or 11/4 in. of lateral travel to
either side of a neutral, or centered, position when the sideframe is
undeflected.

[0253]The lower ends of the springs of the entire spring group, identified
generally as 58, seat in lower spring seat 52. Lower spring seat 52 may
be laid out as a tray with an upturned rectangular peripheral lip.
Although truck 22 employs a spring group in a 3×3 arrangement, this
is intended to be generic, and to represent a range of variations. They
may represent 3×5, 2×4, 3:2:3 or 2:3:2 arrangement, or some
other, and may include a hydraulic snubber, or such other arrangement of
springs may be appropriate for the given service for the railcar for
which the truck is intended.

[0254]FIGS. 2a-2g

[0255]The rocking interface surface of the bearing adapter might have a
crown, or a concave curvature, like a swing motion truck, by which a
rolling contact on the rocker permits lateral swinging of the side frame.
The bearing adapter to pedestal seat interface might also have a
fore-and-aft curvature, whether a crown or a depression, and that, for a
given vertical load, this crown or depression might tend to present a
more or less linear resistance to deflection in the longitudinal
direction, much as a spring or elastomeric pad might do.

[0256]For surfaces in rolling contact on a compound curved surface (i.e.,
having curvatures in two directions) as shown and described herein, the
vertical stiffness may be approximated as infinite (i.e. very large as
compared to other stiffnesses); the longitudinal stiffness in translation
at the point of contact can also be taken as infinite, the assumption
being that the surfaces do not slip; the lateral stiffness in translation
at the point of contact can be taken as infinite, again, provided the
surfaces do not slip. The rotational stiffness about the vertical axis
may be taken as zero or approximately zero. By contrast, the angular
stiffnesses about the longitudinal and transverse axes are non-trivial.
The lateral angular stiffnesses may tend to determine the equivalent
pendulum stiffnesses for the sideframe more generally.

[0257]The stiffness of a pendulum is directly proportional to the weight
on the pendulum. Similarly, the drag on a rail car wheel, and the wear to
the underlying track structure, is a function of the weight borne by the
wheel. For this reason, the desirability of self steering may be greatest
for a fully laden car, and a pendulum may tend to maintain a general
proportionality between the weight borne by the wheel and the stiffness
of the self-steering mechanism as the lading increases.

[0258]Truck performance may vary with the friction characteristics of the
damper surfaces. Wedges have been used that have tended to employ dampers
in which the dynamic and static coefficients of friction may have been
significantly different, yielding a stick-slip phenomenon that may not
have been entirely advantageous. In some embodiments herein the feature
of a self-steering capability may be combined with dampers that have a
reduced tendency to stick-slip operation. Furthermore, while bearing
adapters may be formed of relatively low cost materials, such as cast
iron, in some embodiments an insert of a different material may be used
for the rocker. Further, some embodiments may employ a member that may
tend to center the rocker on installation, and that may tend to perform
an auxiliary centering function to tend to urge the rocker to operate
from an at rest minimum energy position.

[0259]FIGS. 2a-2g show an embodiment of bearing adapter and pedestal seat
assembly. Bearing adapter 44 has a lower portion 112 that is formed to
accommodate, and to seat upon, bearing 46, that is itself mounted on the
end of a shaft, namely an end of axle 48. Bearing adapter 44 has an upper
portion 114 that has a centrally located, upwardly protruding fitting in
the nature of a male bearing adapter interface portion 116. A mating
fitting, in the nature of a female rocker seat interface portion 118 may
be rigidly mounted within the roof 120 of the sideframe pedestal. To that
end, laterally extending lugs 122 are mounted centrally with respect to
pedestal roof 120. The upper fitting 40, whichever type it may be, has a
body that may be in the form of a plate 126 having, along its
longitudinally extending, lateral margins a set of upwardly extending
lugs or ears, or tangs 124 separated by a notch, that bracket, and
tightly engage lugs 122, thereby locating upper fitting 40 in position,
with the back of the plate 126 of fitting 40 abutting the flat, load
transfer face of roof 120. Upper fitting 40 may be a pedestal seat
fitting with a hollowed out female bearing surface, namely portion 118.
As shown in FIG. 2g, when the sideframes are lowered over the wheel sets,
the end reliefs, or channels 128 lying between the bearing adapter corner
abutments 132 seat between the respective side frame pedestal jaws 130.
With the sideframes in place, bearing adapter 44 is thus captured in
position with the male and female portions (116 and 118) of the adapter
interface in mating engagement.

[0260]Male portion 116 (FIG. 2d) has been formed to have a generally
upwardly facing surface 142 that has both a first curvature r1 to
permit rocking in the longitudinal direction, and a second curvature
r2 (FIG. 2c) to permit rocking (i.e., swing motion of the sideframe)
in the transverse direction. Similarly, in the general case, female
portion 118 has a surface having a first radius of curvature R1 in
the longitudinal direction, and a second radius of curvature R2 in
the transverse direction. The engagement of r1 with R1 may tend
to permit a rocking motion in the longitudinal direction, with resistance
to rocking displacement being proportional to the weight on the wheel.
That is to say, the resistance to angular deflection is proportional to
weight rather than being a fixed spring constant. This may tend to yield
passive self-steering in both the light car and fully laden conditions.
This relationship is shown in FIGS. 2d and 2e. FIG. 2d shows the
centered, or at rest, non-deflected position of the longitudinal rocking
elements. FIG. 2e shows the rocking elements at their condition of
maximum longitudinal deflection. FIG. 2d represents a local, minimum
potential energy condition for the system. FIG. 2e represents a system in
which the potential energy has been increased by virtue of the work done
by force F acting longitudinally in the horizontal plane through the
center of the axle and bearing, CB, which will tend to yield an
incremental increase in the height of the pedestal. Put differently, as
the axle is urged to deflect by the force, the rocking motion may tend to
raise the car, and thereby to increase its potential energy.

[0261]The limit of travel in the longitudinal direction is reached when
the end face 134 of bearing adapter 44 extending between corner abutments
132, contacts one or another of travel limiting abutment faces 136 of the
thrust blocks of jaws 130. In general, the deflection may be measured
either by the angular displacement of the axle centerline, θ1,
or by the angular displacement of the rocker contact point on radius r1,
shown as θ2. End face 134 of bearing adapter 44 is planar, and
is relieved, or inclined, at an angle η from the vertical. As shown
in FIG. 2g, abutment face 136 may have a round, cylindrical arc, with the
major axis of the cylinder extending vertically. A typical maximum radius
R3 for this surface is 34 inches. When bearing adapter 44 is fully
deflected through angle η, end face 134 is intended to meet abutment
face 136 in line contact. When this occurs, further longitudinal rocking
motion of the male surface (of portion 116) against the female surface
(of portion 118) is inhibited. Thus jaws 130 constrain the arcuate
deflection of bearing adapter 44 to a limited range. A typical range for
η might be about 3 degrees of arc. A typical maximum value of
δlong may be about +/- 3/16'' to either side of the vertical,
at rest, center line.

[0262]Similarly, as shown in FIGS. 2b and 2c, in the transverse direction,
the engagement of r2 with R2 may tend to permit lateral rocking
motion, as may be in the manner of a swing motion truck. FIG. 2b shows a
centered, at rest, minimum potential energy position of the lateral
rocking system. FIG. 2c shows the same system in a laterally deflected
condition. In this instance δ2 is roughly
(Lpendulum-r2) Sinφ, where, for small angles Sinφ is
approximately equal to φ. Lpendulum may be taken as the at rest
difference in height between the center of the bottom spring seat, 52,
and the contact interface between the male and female portions 116 and
118.

[0263]When a lateral force is applied at the centerplate of the truck
bolster, a reaction force is, ultimately, provided at the meeting of the
wheels with the rail. The lateral force is transmitted from the bolster
into the main spring groups, and then into a lateral force in the spring
seats to deflect the bottom of the pendulum. The reaction is carried to
the bearing adapter, and hence into the top of the pendulum. The pendulum
will then deflect until the weight on the pendulum, multiplied by the
moment arm of the deflected pendulum is sufficient to balance the moment
of the lateral moment couple acting on the pendulum.

[0264]This bearing adapter to pedestal seat interface assembly is biased
by gravity acting on the pendulum toward a central, or "at rest"
position, where there is a local minimum of the potential energy in the
system. The fully deflected position shown in FIG. 2c may correspond to a
deflection from vertical of the order of less than 10 degrees (and
preferably less than 5 degrees) to either side of center, the actual
maximum being determined by the spacing of gibbs 106 and 108 relative to
plate 104. Although in general R1 and R2 may differ, so the
female surface is an outside section of a torus, for R1 and R2
may be the same, i.e., so that the bearing surface of the female fitting
is formed as a portion of a spherical surface, having neither a major nor
a minor axis, but merely being formed on a spherical radius. R1 and
R2 give a self-centering tendency. That tendency may be quite
gentle. Further, and again in the general condition, the smallest of
R1 and R2 may be equal to or larger than the largest of r1
and r2. If so, then the contact point may have little, if any,
ability to transmit torsion acting about an axis normal to the rocking
surfaces at the point of contact, so the lateral and longitudinal rocking
motions may tend to be torsionally de-coupled, and hence it may be said
that relative to this degree of freedom (rotation about the vertical, or
substantially vertical axis normal to the rocking contact interface
surfaces) the interface is torsionally compliant (that is, the resistance
to torsional deflection about the axis through the surfaces at the point
of contact may tend to be much smaller than, for example, resistance to
lateral angular deflection). For small angular deflections, the torsional
stiffness about the normal axis at the contact point, this condition may
sometimes be satisfied even where the smaller of the female radii is less
than the largest male radius. Although it is possible for r1 and
r2 to be the same, such that the crowned surface of the bearing
adapter (or the pedestal seat, if the relationship is inverted) is a
portion of a spherical surface, in the general case r1 and r2
may be different, with r1 perhaps tending to be larger, possibly
significantly larger, than r2. In general, whether or not r1
and r2 are equal, R1 and R2 may be the same or different.
Where r1 and r2 are different, the male fitting engagement
surface may be a section of the surface of a torus. It may also be noted
that, provided the system may tend to return to a local minimum energy
state (i.e., that is self-restorative in normal operation) in the limit
either or both of R1 and R2 may be infinitely large such that
either a cylindrical section is formed or, when both are infinitely
large, a planar surface may be formed. In the further alternative, it may
be that r1=r2, and R1=R2. In one embodiment r1 may be
the same as r2, and may be about 40 inches (+/-5'') and R1 may
the same as R2, and both may be infinite such that the female
surface is planar.

[0265]Other embodiments of rocker geometry may be considered. In one
embodiment R1=R2=15 inches, r1=85/8 inches and
r2=5''. In another embodiment, R1=R2=15 inches, and
r1=10'' and r2=85/8'' (+/-). In another embodiment r1=85/8,
r2=5'', R1=R2=12'' in still another embodiment
r1=121/2'', r2=85/8'' and R1=R2=15''.

[0266]The radius of curvature of the male longitudinal rocker, r1,
may be less than 60 inches, and may lie in the range of 5 to 50 inches,
may lie in the range of 8 to 40 inches, and may be about 15 inches.
R1 may be infinite, or may be less than 100 inches, and may be in
the range of 10 to 60 inches, or in the narrower range of 12 to 40
inches, and may be in the range of 1 1/10 to 4 times the size of r1.

[0267]The radius of curvature of the male lateral rocker, r2, may be
between 30 and 50 inches. Alternatively in another type of truck,
r2, may be less than about 25 or 30 in., and may lie in the range of
about 5 to 20 inches. r2 may lie in the range of about 8 to 16
inches, and may be about 10 inches. Where line contact rocking motion is
used, r2 may perhaps be somewhat smaller than otherwise, perhaps in
the range of 3 to 10 inches, and perhaps being about 5 inches.

[0268]R2 may be less than 60 inches, and may be less than about 25 or
30 inches, then being less than half the 60 inch crown radius noted
above. Alternatively, R2 may lie in the range of 6 to 40 inches, and
may lie in the range of 5 to 15 inches in the case of rolling line
contact. R2 may be between 11/2 to 4 times as large as r2. In
one embodiment R2 may be roughly twice as large as r2,
(+/-20%). Where line contact is employed, R2 may be in the range of
5 to 20 inches, or more narrowly, 8 to 14 inches.

[0269]Where a spherical male rocker is used on a spherical female cap, in
some embodiments the male radius may be in the range of 8-13 in., and may
be about 9 in.; the female radius may be in the range of 11-16 in., and
may be about 12 in. Where a torus, or elliptical surface is employed, in
one embodiment the lateral male radius may be about 7 in., the
longitudinal male radius may be about 10 inches, the lateral female
radius may be about 12 in. and the longitudinal female radius may be
about 15 in. Where a flat female rocker surface is used, and a male
spherical surface is used, the male radius of curvature may be in the
range of about 20 to about 50 in., and may lie in the narrower range of
30 to 40 in.

[0270]Many combinations are possible, depending on loading, intended use,
and rocker materials. In each case the mating male and female rocker
surfaces may tend to be chosen to yield a physically reasonable pairing
in terms of expected loading, anticipated load history, and operational
life. These may vary.

[0271]The rocker surfaces herein may tend to be formed of a relatively
hard material, which may be a metal or metal alloy material, such as a
steel or a material of comparable hardness and toughness. Such materials
may have elastic deformation at the location of rocking contact in a
manner analogous to that of journal or ball bearings. Nonetheless, the
rockers may be taken as approximating the ideal rolling point or line
contact (as may be) of infinitely stiff members. This is to be
distinguished from materials in which deflection of an elastomeric
element be it a pad, or block, of whatever shape, may be intended to
determine a characteristic of the dynamic or static response of the
element.

[0272]In one embodiment the lateral rocking constant for a light car may
be in the range of about 48,000 to 130,000 in-lbs per radian of angular
deflection of the side frame pendulum, or, 260,000 to 700,000 in-lbs per
radian for a fully laded car, or more generically, about 0.95 to 2.6
in-lbs per radian per pound of weight borne by the pendulum.
Alternatively, for a light (i.e., empty) car the stiffness of the
pendulum may be in the range 3,200 to 15,000 lbs per inch, and 22,000 to
61,000 lbs per inch for a fully laden 110 ton truck, or, more
generically, in the range of 0.06 to 0.160 lbs per inch of lateral
deflection per pound weight borne by the pendulum, as measured at the
bottom spring seat.

[0273]The male and female surfaces may be inverted, such that the female
engagement surface is formed on the bearing adapter, and the male
engagement surface is formed on the pedestal seat. It is a matter of
terminology which part is actually the "seat", and which is the "rocker".
Sometimes the seat may be assumed to be the part that has the larger
radius, and which is usually thought of as being the stationary
reference, while the rocker is taken to be the part with the smaller
radius, that "rocks" on the stationary seat. However, this is not always
so. At root, the relationship is of mating parts, whether male or female,
and there is relative motion between the parts, or fittings, whether the
fittings are called a "seat" or a "rocker". The fittings mate at a force
transfer interface. The force transfer interface moves as the parts that
co-operate to define the rocking interface rock on each other, whichever
part may be, nominally, the male part or the female part. One of the
mating parts or surfaces is part of the bearing adapter, and another is
part of the pedestal. There may be only two mating surfaces, or there may
be more than two mating surfaces in the overall assembly defining the
dynamic interface between the bearing adapter and the pedestal fitting,
or pedestal seat, however it may be called.

[0274]Both female radii R1 and R2 may not be on the same
fitting, and both male radii r1 and r2 may not be on the same
fitting. That is, they may be combined to form saddle shaped fittings in
which the bearing adapter has an upper surface that has a male fitting in
the nature of a longitudinally extending crown with a laterally extending
axis of rotation, having the radius of curvature is r1, and a female
fitting in the nature of a longitudinally extending trough having a
lateral radius of curvature R2. Similarly, the pedestal seat fitting
may have a downwardly facing surface that has a transversely extending
trough having a longitudinally oriented radius of curvature R1, for
engagement with r1 of the crown of the bearing adapter, and a
longitudinally running, downwardly protruding crown having a transverse
radius of curvature r2 for engagement with R2 of the trough of
the bearing adapter.

[0275]In a sense, a saddle shaped surface is both a seat and a rocker,
being a seat in one direction, and a rocker in the other. As noted above,
the essence is that there are two small radii, and two large (or possibly
even infinite) radii, and the surfaces form a mating pair that engage in
rolling contact in both the lateral and longitudinal directions, with a
central local minimum potential energy position to which the assembly is
biased to return. It may also be noted that the saddle surfaces can be
inverted such that the bearing adapter has r2 and R1, and the
pedestal seat fitting has r1 and R2. In either case, the
smallest of R1 and R2 may be larger than, or equal to, the
largest of r1 and r2, and the mating saddle surfaces may tend
to be torsionally uncoupled as noted above.

[0276]FIG. 3a

[0277]FIG. 3a shows an alternate embodiment of wheelset to sideframe
interface assembly, indicated most generally as 150. The pedestal region
of sideframe 151, as shown in FIG. 3a, is substantially similar to those
shown in the previous examples, and may be taken as being the same except
insofar as may be noted. Similarly, bearing 152 may be taken as
representing the location of the end of a wheelset more generally, with
the wheelset to sideframe interface assembly including those items,
members or elements that are mounted between bearing 152 and sideframe
151. Bearing adapter 154 may be generally similar to bearing adapter 44
in terms of its lower structure for seating on bearing 152. As with the
bodies of the other bearing adapters described herein, the body of
bearing adapter 154 may be a casting or a forging, or a machined part,
and may be made of a material that may be a relatively low cost material,
such as cast iron or steel, and may be made in generally the same manner
as bearing adapters have been made heretofore. Bearing adapter 154 may
have a bi-directional rocker 153 employing a compound curvature of first
and second radii of curvature according to one or another of the possible
combinations of male and female radii of curvature discussed herein.
Bearing adapter 154 may differ from those described above in that the
central body portion 155 of the adapter has been trimmed to be shorter
longitudinally, and the inside spacing between the corner abutment
portions has been widened somewhat, to accommodate the installation of an
auxiliary centering device, or centering member, or centrally biased
restoring member in the nature of, for example, elastomeric bumper pads,
such as those identified as resilient pads, or members 156. Members 156
may be considered a form of restorative centering element, and may also
be termed "snubbers" or "bumper" pads. A pedestal seat fitting having a
mating rocking surface for permitting lateral and longitudinal rocking,
is identified as 158. As with the other pedestal seat fittings shown and
described herein, fitting 158 may be made of a hard metal material, which
may be a grade of steel. The engagement of the rocking surfaces may,
again, tend to have low resistance to torsion about a predominantly
vertical axis through the point of contact.

[0278]FIG. 3b

[0279]In FIG. 3b, a bearing adapter 160 is substantially similar to
bearing adapter 154, but differs in having a central recess, socket,
cavity or accommodation, indicated generally as 161, for receiving an
insert identified as a first, or lower, rocker member 162. As with
bearing adapter 154, the main, or central portion of the body 159 of
bearing adapter 160 may be of shorter longitudinal extent than might
otherwise be the case, being truncated, or relieved, to accommodate
resilient members 156.

[0280]Accommodation 161 may have a plan view form whose periphery may
include one or more keying, or indexing, features or fittings, of which
cusps 163 may be representative. Cusps 163 may receive mating keying, or
indexing, features or fittings of rocker member 162, of which lobes 164
may be taken as representative examples. Cusps 163 and lobes 164 may fix
the angular orientation of the lower, or first, rocker member 162 such
that the appropriate radii of curvature may be presented in each of the
lateral and longitudinal directions. For example, cusps 163 may be spaced
unequally about the periphery of accommodation 161 (with lobes 164 being
correspondingly spaced about the periphery of the insert member 162) in a
specific spacing arrangement to prevent installation in an incorrect
orientation, (such as 90 degrees out of phase). For example, one cusp may
be spaced 80 degrees of arc about the periphery from one neighboring
cusp, and 100 degrees of arc from another neighboring cusp, and so on to
form a rectangular pattern. Many variations are possible.

[0281]While body 159 of bearing adapter 160 may be made of cast iron or
steel, the insert, namely first rocker member 162, may be made of a
different material that may have higher hardness. That different material
may present a hardened metal rocker surface such as may have been
manufactured by a different process. For example, the insert, member 162,
may be made of a metal, such as a tool steel, or of a steel such as may
be used in the manufacture of ball bearings. The material may have a
Young's modulus in excess of 2.5×107 p.s.i., such as may be
about 3.0×107 p.s.i. such as might be typical of a steel. The
material may have a yield stress in excess of 100 kpsi, and that yield
stress may be in excess of 200 kpsi in some embodiments. Furthermore,
upper surface 165 of insert member 162, which includes that portion that
is in rocking engagement with the mating pedestal seat 168, may be
machined or otherwise formed to a high degree of smoothness, akin to a
ball bearing surface, and may be heat treated, to give a finished bearing
part approximating ideal rolling point or line contact rather then an
interface relying upon deflection of the body of the element of an
elastomeric pad or block. That is, the rocking stiffness may rely on the
geometry of the pendulum, namely the radii of the curvature of the
rocking surfaces and the length of the pendulum as distinct from elastic
deflection of the material, as in an elastomeric rubber or polymer based
pad for example and that may demonstrate significant hysteresis. Put
differently, the vertical stiffness of the rocker, based on its bulk
material properties, may be two or more orders of magnitude greater than
its lateral rocking stiffness, which is based on geometry, such that
approximation of the vertical stiffness as being infinite by comparison
is physically reasonable. Similarly, the lateral stiffness of the rocker
in lateral shear, as manifested by bodily deflection of the rocker
elements due to the bulk properties of the rocker materials, may be taken
as being at least two orders of magnitude (if not many orders of
magnitude) greater than the lateral rocking stiffness of the pendulum
such that it is physically reasonable to consider the material to
approximate infinite stiffness as compared to the rocker geometry. The
foregoing commentary may be taken as applying to each of the embodiments
described herein in which there is reference to rolling point or line
contact.

[0282]Similarly, pedestal seat 168 may be made of a hardened material,
such as a tool steel or a steel from which bearings are made, formed to a
high level of smoothness, and heat treated as may be appropriate of
appropriate modulus of elasticity and yield stress, which may be in the
ranges discussed above, having a surface formed to mate with surface 165
of rocker member 162. Alternatively, pedestal seat 168 may have an
accommodation indicated as 167, and an insert member, identified as upper
or second rocker member 166, analogous to accommodation 161 and insert
member 162, with keying or indexing such as may tend to cause the parts
to seat in the correct orientation. Member 166 may be formed of a hard
material in a manner similar to member 162, and may have a downward
facing rocking surface 157, which may be machined or otherwise formed to
a high degree of smoothness, akin to a ball or roller bearing surface,
and may be heat treated, to give a finished bearing part surface for
mating, rocking engagement with surface 165. Where rocker member 162 has
both male radii, and the female radii of curvature are both infinite such
that the female surface is planar, a wear member having a planar surface
such as a spring clip may be mounted in a sprung interference fit in the
pedestal roof in lieu of pedestal seat 168. In one embodiment, the spring
clip may be a clip on "Dyna-Clip"® pedestal roof wear plate such as
supplied by TransDyne Inc. Such a clip is shown in an isometric view in
FIG. 8a as item 354.

[0283]FIG. 3e

[0284]FIG. 3e shows an alternate embodiment of wheelset to sideframe
interface assembly, indicated generally as 170. Assembly 170 may include
a bearing adapter 171, a pair of resilient members 156, a rocking
assembly that may include a boot, resilient ring or retainer, 172, a
first rocker member 173, and a second rocker member 174. A pedestal seat
may be provided to mount in the roof of the pedestal as described above,
or second rocker member 174 may mount directly in the pedestal roof.

[0285]Bearing adapter 171 is generally similar to bearing adapter 44, or
154, in terms of its lower structure for seating on bearing 152. The body
of bearing adapter 171 may be a casting or a forging, or a machined part,
and may be made of a material that may be a relatively low cost material,
such as cast iron or steel. Bearing adapter 171 may be provided with a
central recess, socket, cavity or accommodation, indicated generally as
176, for receiving rocker member 173 and rocker member 174, and retainer
172. The ends of the main portion of the body of bearing adapter 171 may
be of relatively short extent to accommodate resilient members 156.
Accommodation 176 may have the form of a circular opening, that may have
a radially inwardly extending flange 177, whose upwardly facing surface
178 defines a circumferential land upon which to seat first rocker member
173. Flange 177 may also include drain holes 178, such as may be 4 holes
formed on 90 degree centers, for example. Rocker member 173 has a
spherical engagement surface. First rocker member 173 may include a
thickened central portion, and a thinner radially distant peripheral
portion, having a lower radial edge, or margin, or land, for seating
upon, and for transferring vertical loads into, flange 177. In an
alternate embodiment, a non-galling, relatively soft annular gasket, or
shim, whether made of a suitable brass, bronze, copper, or other material
may be employed on flange 177 under the land. First rocker member 173 may
be made of a different material from the material from which the body of
bearing adapter 156 is made more generally. That is to say, rocker member
173 may be made of a hard, or hardened material, such as a tool steel or
a steel such as might be used in a bearing, that may be harder and may be
finished to a generally higher level of precision, and to a finer degree
of surface roughness than the body of bearing adapter 156 more generally.
Such a material may be suitable for rolling contact operation under high
contact pressures.

[0286]Second rocker member 174 may be a disc of circular shape (in plan
view) or other suitable shape having an upper surface for seating in
pedestal seat 168, or, in the event a pedestal seat member is not used,
then formed directly to mate with the pedestal roof having an integrally
formed seat. First rocker member 173 may have an upper, or rocker surface
175, having a profile such as may give bi-directional lateral and
longitudinal rocking motion when used in conjunction with the mating
second, or upper rocker member, 174. Second rocker member 174 may be made
of a different material from the material from which the body of bearing
adapter 171, or the pedestal seat, is made more generally. Second rocker
member 174 may be made of a hard, or hardened material, such as a tool
steel or a steel such as might be used in a bearing, that may be harder
and may be finished to a generally higher level of precision, and to a
finer degree of surface roughness than the body of sideframe 151 more
generally. Such a material may be suitable for rolling contact operation
under high contact pressures, particularly as when operated in
conjunction with first rocker member 173. Where an insert of dissimilar
material is used, that material may tend to be rather more costly than
the cast iron or relatively mild steel from which bearing adapters may
otherwise tend to be made. Further still, an insert of this nature may be
removed and replaced when worn, either on the basis of a scheduled
rotation, or as the need may arise.

[0287]Resilient member 172 may be made of a composite or polymeric
material, such as a polyurethane. Resilient member 172 may also have
apertures, or reliefs 179 such as may be placed in a position for
co-operation with corresponding drain holes 178. The wall height of
resilient member 172 may be sufficiently tall to engage the periphery of
first rocker member 173. Further, a portion of the radially outwardly
facing peripheral edge of the second, upper, rocking member 174, may also
lie within, or may be partially overlapped by, and may possibly slightly
stretchingly engage, the upper margin of resilient member 172 in a close,
or interference, fit manner, such that a seal may tend to be formed to
exclude dirt or moisture. In this way the assembly may tend to form a
closed unit. In that regard, such space as may be formed between the
first and second rockers 173, 174 inside the dirt exclusion member may be
packed with a lubricant, such as a lithium or other suitable grease.

[0288]FIGS. 4a-4e

[0289]As shown in FIGS. 4a-4e, resilient members 156 may have the general
shape of a channel, having a central, or back, or transverse, or web
portion 181, and a pair of left and right hand, flanking wing portions
182, 183. Wing portions 182 and 183 may tend to have downwardly and
outwardly tending extremities that may tend to have an arcuate lower edge
such as may seat over the bearing casing. The inside width of wing
portions 182 and 183 may be such as to seat snugly about the sides of
thrust blocks 180. A transversely extending lobate portion 185, running
along the upper margin of web portion 181, may seat in a radiused rebate
184 between the upper margin of thrust blocks 180 and the end of pedestal
seat 168. The inner lateral edge 186 of lobate portion 185 may tend to be
chamfered, or relieved, to accommodate, and to seat next to, the end of
pedestal seat 168.

[0290]It may be desirable for the rocking assembly at the wheelset to
sideframe interface to tend to maintain itself in a centered condition.
As noted, the torsionally de-coupled bi-directional rocker arrangements
disclosed herein may tend to have rocking stiffnesses that are
proportional to the weight placed upon the rocker. Where a longitudinal
rocking surface is used to permit self-steering, and the truck is
experiencing reduced wheel load, (such as may approach wheel lift), or
where the car is operating in the light car condition, it may be helpful
to employ an auxiliary restorative centering element that may include a
biasing element tending to urge the bearing adapter to a longitudinally
centered position relative to the pedestal roof, and whose restorative
tendency may be independent of the gravitational force experienced at the
wheel. That is, when the bearing adapter is under less than full load, or
is unloaded, it may be desirable to maintain a bias to a central
position. Resilient members 156 described above may operate to urge such
centering.

[0291]FIGS. 3c and 3d illustrate the spatial relationship of the sandwich
formed by (a) the bearing adapter, for example, bearing adapter 154; (b)
the centering member, such as, for example, resilient members 156; and
(c) the pedestal jaw thrust blocks, 180. Ancillary details such as, for
example, drain holes or phantom lines to show hidden features have been
omitted from FIGS. 3c and 3d for clarity. When resilient member 156 is in
place, bearing adapter 154 (or 171, as may be); may tend to be centered
relative to jaws 180. As installed, the snubber (member 156) may seat
closely about the pedestal jaw thrust lug, and may seat next to the
bearing adapter end wall and between the bearing adapter corner abutments
in a slight interference fit. The snubber may be sandwiched between, and
may establish the spaced relative position of, the thrust lug and the
bearing adapter and may provide an initial central positioning of the
mating rocker elements as well as providing a restorative bias. Although
bearing adapter 154 may still rock relative to the sideframe, such
rocking may tend to deform (typically, locally to compress) a portion of
member 156, and, being elastic, member 156 may tend to urge bearing
adapter 154 toward a central position, whether there is much weight on
the rocking elements or not. Resilient member 156 may have a restorative
force-deflection characteristic in the longitudinal direction that is
substantially less stiff than the force deflection characteristic of the
fully loaded longitudinal rocker (perhaps one to two orders of magnitude
less), such that, in a fully loaded car condition, member 156 may tend
not significantly to alter the rocking behavior. In one embodiment member
156 may be made of a polyurethane having a Young's modulus of some 6,500
p.s.i. In another embodiment the Young's modulus may be about 13,000
p.s.i. The Young's modulus of the elastomeric material may be in the
range of 4 to 20 k.p.s.i. The placement of resilient members 156 may tend
to center the rocking elements during installation. In one embodiment,
the force to deflect one of the snubbers may be less than 20% of the
force to deflect the rocker a corresponding amount under the light car
(i.e., unloaded) condition, and may, for small deflections, have an
equivalent force/deflection curve slope that may be less than 10% of the
force deflection characteristic of the longitudinal rocker.

[0292]FIG. 5

[0293]Thus far only primary wedge angles have been discussed. FIG. 5 shows
an isometric view of an end portion of a truck bolster 210. As with all
of the truck bolsters shown and discussed herein, bolster 210 is
symmetrical about the central longitudinal vertical plane of the bolster
(i.e., cross-wise relative to the truck generally) and symmetrical about
the vertical mid-span section of the bolster (i.e., the longitudinal
plane of symmetry of the truck generally, coinciding with the railcar
longitudinal center line). Bolster 210 has a pair of spaced apart bolster
pockets 212, 214 for receiving damper wedges 216, 218. Pocket 212 is
laterally inboard of pocket 214 relative to the side frame of the truck
more generally. Wear plate inserts 220, 222 are mounted in pockets 212,
214 along the angled wedge face.

[0294]As can be seen, wedges 216, 218 have a primary angle, α as
measured between vertical and the angled trailing vertex 228 of outboard
face 230. For the embodiments discussed herein, primary angle α may
tend to lie in the range of 35-55 degrees, possibly about 40-50 degrees.
This same angle α is matched by the facing surface of the bolster
pocket, be it 212 or 214. A secondary angle β gives the inboard, (or
outboard), rake of the sloped surface 224, (or 226) of wedge 216 (or
218). The true rake angle can be seen by sighting along plane of the
sloped face and measuring the angle between the sloped face and the
planar outboard face 230. The rake angle is the complement of the angle
so measured. The rake angle may tend to be greater than 5 degrees, may
lie in the range of 5 to 20 degrees, and is preferably about 10 to 15
degrees. A modest rake angle may be desirable.

[0295]When the truck suspension works in response to track perturbations,
the damper wedges may tend to work in their pockets. The rake angles
yield a component of force tending to bias the outboard face 230 of
outboard wedge 218 outboard against the opposing outboard face of bolster
pocket 214. Similarly, the inboard face of wedge 216 may tend to be
biased toward the inboard planar face of inboard bolster pocket 212.
These inboard and outboard faces of the bolster pockets may be lined with
a low friction surface pad, indicated generally as 232. The left hand and
right hand biases of the wedges may tend to keep them apart to yield the
full moment arm distance intended, and, by keeping them against the
planar facing walls, may tend to discourage twisting of the dampers in
the respective pockets.

[0296]Bolster 210 includes a middle land 234 between pockets 212, 214,
against which another spring 236 may work. Middle land 234 is such as
might be found in a spring group that is three (or more) coils wide.
However, whether two, three, or more coils wide, and whether employing a
central land or no central land, bolster pockets can have both primary
and secondary angles as illustrated in the example embodiment of FIG. 5a,
with or without wear inserts.

[0297]Where a central land, e.g., land 234, separates two damper pockets,
the opposing side frame column wear plates need not be monolithic. That
is, two wear plate regions could be provided, one opposite each of the
inboard and outboard dampers, presenting planar surfaces against which
the dampers can bear. The normal vectors of those regions may be
parallel, the surfaces may be co-planar and perpendicular to the long
axis of the side frame, and may present a clear, un-interrupted surface
to the friction faces of the dampers.

[0298]FIG. 1e

[0299]FIG. 1e shows an example of a three piece railroad car truck, shown
generally as 250. Truck 250 has a truck bolster 252, and a pair of
sideframes 254. The spring groups of truck 250 are indicated as 256.
Spring groups 256 are spring groups having three springs 258 (inboard
corner), 260 (center) and 262 (outboard corner) most closely adjacent to
the sideframe columns 254. A motion calming, kinematic energy dissipating
element, in the nature of a friction damper 264, 266 is mounted over each
of central springs 260.

[0300]Friction damper 264, 266 has a substantially planar friction face
268 mounted in facing, planar opposition to, and for engagement with, a
side frame wear member in the nature of a wear plate 270 mounted to
sideframe column 254. The base of damper 264, 266 defines a spring seat,
or socket 272 into which the upper end of central spring 260 seats.
Damper 264, 266 has a third face, being an inclined slope or hypotenuse
face 274 for mating engagement with a sloped face 276 inside sloped
bolster pocket 278. Compression of spring 260 under an end of the truck
bolster may tend to load damper 264 or 266, as may be, such that friction
face 268 is biased against the opposing bearing face of the sideframe
column, 280. Truck 250 also has wheelsets whose bearings are mounted in
the pedestal 284 at either ends of the side frames 254. Each of these
pedestals may accommodate one or another of the sideframe to bearing
adapter interface assemblies described above and may thereby have a
measure of self steering.

[0301]In this embodiment, vertical face 268 of friction damper 264, 266
may have a bearing surface having a co-efficient of static friction, :s,
and a co-efficient of dynamic or kinetic friction, :k, that may tend to
exhibit little or no "stick-slip" behavior when operating against the
wear surface of wear plate 270. In one embodiment, the coefficients of
friction are within 10% of each other. In another embodiment the
coefficients of friction are substantially equal and may be substantially
free of stick-slip behavior. In one embodiment, when dry, the
coefficients of friction may be in the range of 0.10 to 0.45, may be in
the narrower range of 0.15 to 0.35, and may be about 0.30. Friction
damper 264, 266 may have a friction face coating, or bonded pad 286
having these friction properties, and corresponding to those inserts or
pads described in the context of FIGS. 6a-6c, and FIGS. 7a-7h. Bonded pad
286 may be a polymeric pad or coating. A low friction, or controlled
friction pad or coating 288 may also be employed on the sloped surface of
the damper. In one embodiment that coating or pad 288 may have
coefficients of static and dynamic friction that are within 20%, or, more
narrowly, 10% of each other. In another embodiment, the coefficients of
static and dynamic friction are substantially equal. The co-efficient of
dynamic friction may be in the range of 0.10 to 0.30, and may be about
0.20.

[0302]FIGS. 6a to 6c

[0303]The bodies of the damper wedges themselves may be made from a
relatively common material, such as a mild steel or cast iron. The wedges
may then be given wear face members in the nature of shoes, wear inserts
or other wear members, which may be intended to be consumable items. In
FIG. 6a, a damper wedge is shown generically as 300. The replaceable,
friction modification consumable wear members are indicated as 302, 304.
The wedges and wear members may have mating male and female mechanical
interlink features, such as the cross-shaped relief 303 formed in the
primary angled and vertical faces of wedge 300 for mating with the
corresponding raised cross shaped features 305 of wear members 302, 304.
Sliding wear member 302 may be made of a material having specified
friction properties, and may be obtained from a supplier of such
materials as, for example, brake and clutch linings and the like, such as
Railway Friction Products. The materials may include materials that are
referred to as being non-metallic, low friction materials, and may
include UHMW polymers, and may be formed as removable and replaceable
pads or blocks or linings.

[0304]Although FIGS. 6a and 6c show consumable inserts in the nature of
wear plates, namely wear members 302, 304 the entire bolster pocket may
be made as a replaceable part. It may be a high precision casting, or may
include a sintered powder metal assembly having suitable physical
properties. The part so formed may then be welded into place in the end
of the bolster.

[0305]The underside of the wedges described herein, wedge 300 being
typical in this regard, may have a seat, or socket 307, for engaging the
top end of the spring coil, whichever spring it may be, spring 262 being
shown as typically representative. Socket 307 serves to discourage the
top end of the spring from wandering away from the intended generally
central position under the wedge. A bottom seat, or boss, for
discouraging lateral wandering of the bottom end of the spring is shown
in FIG. 1e as item 308. It may be noted that wedge 300 has a primary
angle, but does not have a secondary rake angle. In that regard, wedge
300 may be used as damper 264, 266 of truck 250 of FIG. 1e, for example,
and may provide friction damping with little or no "stick-slip" behavior,
but rather friction damping for which the coefficients of static and
dynamic friction are equal, or only differ by a small (less than about
20%, perhaps less than 10%) difference. Wedge 300 may be used in truck
250 in conjunction with a bi-directional bearing adapter of any of the
embodiments described herein. Wedge 300 may also be used in a four
cornered damper arrangement, as in truck 22, for example, where wedges
may be employed that may lack secondary angles.

[0306]FIGS. 7a-7h

[0307]Referring to FIGS. 7a-7e, a damper 310 is shown such as may be used
in truck 22, or any of the other double damper trucks described herein,
such as may have appropriately formed, mating bolster pockets. Damper 310
is similar to damper 300, but may include both primary and secondary
angles. Damper 310 may, arbitrarily, be termed a right handed damper
wedge. FIGS. 7a-7e are intended to be generic such that it may be
understood also to represent the left handed, mirror image of a mating
damper with which damper 310 would form a matched pair.

[0308]Wedge 310 has a body 312 that may be made by casting or by another
suitable process. Body 312 may be made of steel or cast iron, and may be
substantially hollow. Body 312 has a first, substantially planar platen
portion 314 having a first face for placement in a generally vertical
orientation in opposition to a sideframe bearing surface, for example, a
wear plate mounted on a sideframe column. Platen portion 314 may have a
rebate, or relief, or depression formed therein to receive a bearing
surface wear member, indicated as member 316. Member 316 may be a
material having specific friction properties when used in conjunction
with the sideframe column wear plate material. For example, member 316
may be formed of a brake lining material, and the column wear plate may
be formed from a high hardness steel. This material may be formed as a
removable and replaceable pad or block.

[0309]Body 312 may include a base portion 318 that may extend rearwardly
from and generally perpendicularly to, platen portion 314. Base portion
318 may have a relief 320 formed therein in a manner to form, roughly,
the negative impression of an end of a spring coil, such as may receive a
top end of a coil of a spring of a spring group, such as spring 262. Base
portion 318 may join platen portion 314 at an intermediate height, such
that a lower portion 321 of platen portion 314 may depend downwardly
therebeyond in the manner of a skirt. That skirt portion may include a
corner, or wrap around portion 322 formed to seat around a portion of the
spring.

[0310]Body 312 may also include a diagonal member in the nature of a
sloped member 324. Sloped member 324 may have a first, or lower end
extending from the distal end of base 318 and running upwardly and
forwardly toward a junction with platen portion 314. An upper region 326
of platen portion 314 may extend upwardly beyond that point of junction,
such that damper wedge 310 may have a footprint having a vertical extent
somewhat greater than the vertical extent of sloped member 324. Sloped
member 324 may also have a socket or seat in the nature of a relief or
rebate 328 formed therein for receiving a sliding face member 330 for
engagement with the bolster pocket wear plate of the bolster pocket into
which wedge 310 may seat. As may be seen, sloped member 324 (and face
member 330) are inclined at a primary angle α, and a secondary
angle β. Sliding face member 330 may be an element of chosen,
possibly relatively low, friction properties (when engaged with the
bolster pocket wear plate), such as may include desired values of
coefficients of static and dynamic friction. In one embodiment the
coefficients of static and dynamic friction may be substantially equal,
may be about 0.2 (+/-20%, or, more narrowly +/-10%), and may be
substantially free of stick-slip behavior.

[0311]In the alternative embodiment of FIG. 7g, a damper wedge 332 is
similar to damper wedge 310, but, in addition to pads or inserts for
providing modified or controlled friction properties on the friction face
for engaging the sideframe column and on the face for engaging the slope
of the bolster pocket, damper wedge 332 may have pads or inserts such as
pad 334 on the side faces of the wedge for engaging the side faces of the
bolster pockets. In this regard, it may be desirable for pad 334 to have
low coefficients of friction, and to tend to be free of stick slip
behavior. The friction materials may be cast or bonded in place, and may
include mechanical interlocking features, such as shown in FIG. 6a, or
bosses, grooves, splines, or the like such as may be used for the same
purpose. Similarly, in the alternative embodiment of FIG. 7h, a damper
wedge 336 is provided in which the slope face insert or pad, and the side
wall insert or pad form a continuous, or monolithic, element, indicated
as 338. The material of the pad or insert may, again, be cast in place,
and may include mechanical interlock features.

[0312]FIGS. 8a-8f

[0313]FIGS. 8a-8f show an alternate bearing adapter assembly to that of
FIG. 3a. The assembly, indicated generally as 350, may differ from that
of FIG. 3a insofar as bearing adapter 344 may have an upper surface 346
that may be a load bearing interface surface of significant extent, that
may be substantially planar and horizontal, such that it may act as a
base upon which to seat a rocker element, 348. Rocker element 348 may
have an upper, or rocker, surface 352 having a suitable profile, such as
a compound curvature having lateral and longitudinal radii of curvature,
for mating with a corresponding rocker engagement surface of a pedestal
seat liner 354. As noted above, in the general case each of the two
rocking engagement surface may have both lateral and longitudinal radii
of curvature, such that there are mating lateral male and female radii,
and mating longitudinal male and female radii. In one embodiment, both
the female radii may be infinite, such that the pedestal seat may have a
planar engagement surface, and the pedestal seat liner may be a wear
liner, or similar device.

[0314]Rocker element 348 may also have a lower surface 356 for seating on,
mating with, and for transferring loads into, upper surface 346 over a
relatively large surface area, and may have a suitable through thickness
for diffusing vertical loading from the zone of rolling contact to the
larger area of the land (i.e., surface 346, or a portion thereof) upon
which rocker element 348 sits. Lower surface 356 may also include a
keying, or indexing feature 358 of suitable shape, and may include a
centering feature 360, both to aid in installation, and to aid in
re-centering rocker element 348 in the event that it should be tempted to
migrate away from the central position during operation. Indexing feature
358 may also include an orienting element for discouraging
mis-orientation of rocker element 348. Indexing feature 358 may be a
cavity 362 of suitable shape to mate with an opposed button 364 formed on
the upper surface 346 of bearing adapter 344. If this shape is
non-circular, it may tend to admit of only one permissible orientation.
The orienting element may be defined in the plan form shape of cavity 362
and button 364. Where the various radii of curvature of rocker element
348 differ in the lateral and longitudinal directions, it may be that two
positions 180 degrees out of phase may be acceptable, whereas another
orientation may not. While an ellipse of differing major and minor axes
may serve this purpose, the shape of cavity 362 and button 364 may be
chosen from a large number of possibilities, and may have a cruciform or
triangular shape, or may include more than one raised feature in an
asymmetrical pattern, for example. The centering feature may be defined
in the tapered, or sloped, flanks 368 and 370 of cavity 362 and 364
respectively, in that, once positioned such that flanks 368 and 370 begin
to work against each other, a normal force acting downward on the
interface may tend to cause the parts to center themselves.

[0315]Rocker element 348 has an external periphery 372, defining a
footprint. Resilient members 374 may be taken as being the same as
resilient members 156, noted above, except insofar as resilient members
374 may have a depending end portion for nesting about the thrust block
of a jaw of the pedestal, and also a predominantly horizontally extending
portion 376 for overlying a substantial portion of the generally flat or
horizontal upper region of bearing adapter 344. That is, the outlying
regions of surface 346 of bearing adapter 344 may tend to be generally
flat, and may tend, due to the general thickness of rocker element 348,
to be compelled to stand in a spaced apart relationship from the opposed,
downwardly facing surface of the pedestal seat, such as may be, for
example, the exposed surface of a wear liner such as item 354, or a seat
such as item 168, or such other mating part as may be suitable. Portion
376 is of a thickness suitable for lying in the gaps so defined, and may
tend to be thinner than the mean gap height so as not to interfere with
operation of the rocker elements. Horizontally extending portion 376 may
have the form of a skirt such as may include a pair of left and right
hand arms or wings 378 and 380 having a profile, when seen in plan view,
for embracing a portion of periphery 372. Resilient member 374 has a
relief 382 defined in the inwardly facing edge. Where rocker member 348
has outwardly extending blisters, or cusps, akin to item 164, relief 382
may function as an indexing or orientation feature. A relatively coarse
engagement of rocker element 348 may tend to result in wings 378 and 380
urging rocker element 348 to a generally centered position relative to
bearing adapter 344. This coarse centering may tend to cause cavity 362
to pick up on button 364, such that rocker member 348 is then urged to
the desired centered position by a fine centering feature, namely the
chamfered flanks 368, 370. The root of portion 376 may be relieved by a
radius 384 adjacent the juncture of surface 346 with the end wall 386 of
bearing adapter 348 to discourage chaffing of resilient member 372, 374
at that location.

[0316]Without the addition of a multiplicity of drawings, it may be noted
that rocker element 348 could, alternatively, be inverted so as to seat
in an accommodation formed in the pedestal roof, with a land facing
toward the roof, and a rocking surface facing toward a mating bearing
adapter, be it adapter 44 or some other.

[0317]FIGS. 9a and 9b

[0318]FIG. 9a shows an alternative arrangement to that of FIG. 3a or FIG.
8a. In the wheelset to sideframe interface assembly of FIG. 9a, indicated
generally as 400, bearing adapter 404 may be substantially similar to
bearing adapter 344, and may have an upper surface 406 and a rocker
element 408 that interact in the same manner as rocker element 348
interacts with surface 346. (Or, in the inverted case, the rocker element
may be seated in the pedestal roof, and the bearing adapter may have a
mating upwardly facing rocker surface). The rocker element may interact
with a pedestal seat fitting 410 such as may be a wear liner seated in
the pedestal roof. Rocker element 408 and the body of bearing adapter 404
may have mating indexing features as described in the context of FIGS. 8a
to 8e.

[0319]Rather than two resilient members, such as items 374, however,
assembly 400 employs a single resilient member 412, such as may be a
monolithic cast material, be it polyurethane or a suitable rubber or
rubberlike material such as may be used, for example, in making an LC pad
or a Pennsy pad. An LC pad is an elastomeric bearing adapter pad
available from Lord Corporation of Erie Pa. An example of an LC pad may
be identified as Standard Car Truck Part Number SCT 5578. In this
instance, resilient member 412 has first and second end portions 414, 416
for interposition between the thrust lugs of the jaws of the pedestal and
the ends 418 and 420 of the bearing adapter. End portions 414, 416 may
tend to be a bit undersize so that, once the roof liner is in place, they
may slide vertically into place on the thrust lugs, possibly in a modest
interference fit. The bearing adapter may slide into place thereafter,
and again, may do so in a slight interference fit, carrying the rocker
element 408 with it into place.

[0320]Resilient member 412 may also have a central or medial portion 422
extending between end portions 414, 416. Medial portion 422 may extend
generally horizontally inward to overlie substantial portions of the
upper surface bearing adapter 404. Resilient member 412 may have an
accommodation 424 formed therein, be it in the nature of an aperture, or
through hole, having a periphery of suitable extent to admit rocker
element 408, and so to permit rocker element 408 to extend at least
partially through member 412 to engage the mating rocking element of the
pedestal seat. It may be that the periphery of accommodation 422 is
matched to the shape of the footprint of rocker element 408 in the manner
described in the context of FIGS. 8a to 8e to facilitate installation and
to facilitate location of rocker element 408 on bearing adapter 404. In
one embodiment resilient member 412 may be formed in the manner of a
Pennsy Pad with a suitable central aperture formed therein.

[0321]FIG. 9b shows a Pennsy pad installation. In this installation, a
bearing adapter is indicated as 430, and an elastomeric member, such as
may be a Pennsy pad, is indicated as 432. On installation, member 432
seats between the pedestal roof and the bearing adapter. The term "Pennsy
pad", or "Pennsy Adapter Plus", refers to a kind of elastomeric pad
developed by Pennsy Corporation of Westchester Pa. One example of such a
pad is illustrated in U.S. Pat. No. 5,562,045 of Rudibaugh et al., issued
Oct. 6, 1996 (and which is incorporated herein by reference). FIG. 9b may
include a pad 432 and bearing adapter of 430 the same, or similar, nature
to those shown and described in the U.S. Pat. No. 5,562,045. The Pennsy
pad may tend to permit a measure of passive steering. The Pennsy pad
installation of FIG. 9b can be installed in the sideframe of FIG. 1a, in
combination with a four cornered damper arrangement, as indicated in
FIGS. 1a-1d. In this embodiment the truck may be a Barber S2HD truck,
modified to carry a damper arrangement, such as a four-cornered damper
arrangement, such as may have an enhanced restorative tendency in the
face of non-square deformation of the truck, having dampers that may
include friction surfaces as described herein.

[0322]FIGS. 10a-10e

[0323]FIG. 10a shows a further alternate embodiment of wheelset to
sideframe interface assembly to that of FIG. 3a or FIG. 8a. In this
instance, bearing adapter 444 may have an upper rocker surface of any of
the configurations discussed above, or may have a rocker element in the
manner of bearing adapter 344.

[0324]The underside of bearing adapter 444 may have not only a
circumferentially extending medial groove, channel or rebate 446, having
an apex lying on the transverse plane of symmetry of bearing adapter 444,
but also a laterally extending underside rebate 448 such as may tend to
lie parallel to the underlying longitudinal axis of the wheelset shaft
and bearing centerline (i.e., the axial direction) such that the
underside of bearing adapter 444 has four corner lands or pads 450
arranged in an array for seating on the casing of the bearing. In this
instance, each of the pads, or lands, may be formed on a curved surface
having a radius conforming to a body of revolution such as the outer
shell of the bearing. Rebate 448 may tend to lie along the apex of the
arch of the underside of bearing adapter 444, with the intersection of
rebates 446 and 448. Rebate 448 may be relatively shallow, and may be
gently radiused into the surrounding bearing adapter body. The body of
bearing adapter 444 is more or less symmetrical about both its
longitudinal central vertical plane (i.e., on installation, that plane
lying vertical and parallel to, if not coincident with, the longitudinal
vertical central plane of the sideframe), and also about its transverse
central plane (i.e., on installation, that plane extending vertically
radially from the center line of the axis of rotation of the bearing and
of the wheelset shaft). It may be noted that axial rebate 448 may tend to
lie at the section of minimum cross-sectional area of bearing adapter
444. Rebates 446 and 448 may tend to divide, and spread, the vertical
load carried through the rocker element over a larger area of the casing
of the bearing, and hence more evenly to distribute the load into the
rollers of the bearing than might otherwise be the case. It is thought
that this may tend to encourage longer bearing life.

[0325]In the general case, bearing adapter 444 may have an upper surface
having a crown to permit self-steering, or may be formed to accommodate a
self-steering apparatus such as an elastomeric pad, such as a Pennsy Pad
or other pad. In the event that a rocker surface is employed, whether by
way of a separable insert, or a disc, or is integrally formed in the body
of the bearing adapter, the location of the contact of the rocker in the
resting position may tend to lie directly above the center of the bearing
adapter, and hence above the intersection of the axial and
circumferential rebates in the underside of bearing adapter 444.

[0326]FIGS. 11a-11f

[0327]FIGS. 11a-11f show views of a bearing adapter 452, a pedestal seat
insert 454 and elastomeric bumper pad members 456, as an assembly for
insertion between bearing 46 and sideframe 26. Bearing adapter 452 and
pad members 456 are generally similar to bearing adapter 171 and members
156, respectively. They differ, however, insofar as bearing adapter 452
has thrust block standoff elements 460, 462 located at either end
thereof, and the lower corners of bumpers 456 have been truncated
accordingly. It may be that for a certain range of deflection, an
elastomeric response is desired, and may be sufficient to accommodate a
high percentage of in-service performance. However, excursion beyond that
range of deflection might tend to cause damage, or reduction in life, to
pad members 456. Standoff elements 460, 462 may act as limiting stops to
bound that range of motion. Standoff elements 460, 462 may have the form
of shelves, or abutments, or stops 466, 468 mounted to, and standing
proud of, the laterally inwardly facing faces of the corner abutment
portions 470, 472 of bearing adapter 452 more generally. As installed,
stops 466, 468 underlie toes 474, 476 of members 456. As may be noted,
toes 474, 476 have a truncated appearance as compared to the toes of
member 356 in order to stand clear of stops 466, 468 on installation. In
the at rest, centered condition, stops 466, 468 may tend to stand clear
of the pedestal jaw thrust blocks by some gap distance. When the lateral
deflection of the elastomer in member 456 reaches the gap distance, the
thrust lug may tend to bottom against stop 466 or 468, as the case may
be. The sheltering width of stops 466, 468 (i.e., the distance by which
they stand proud of the inner face of corner abutment portions 470, 472)
may tend to provide a reserve compression zone for wings 475, 477 and may
thereby tend to prevent them from being unduly squeezed or pinched.
Pedestal seat insert 454 may be generally similar to liner 354, but may
include radiused bulges 480, 482, and a thicker central portion 484.
Bearing adapter 452 may include a central bi-directional rocker portion
486 for mating rocking engagement with the downwardly facing rocking
surface of central portion 484. The mating surfaces may conform to any of
the combinations of bi-directional rocking radii discussed herein. Rocker
portion 486 may be trimmed laterally as at longitudinally running side
shoulders 488, 490 to accommodate bulges 480, 482.

[0328]Bearing adapter 452 may also have different underside grooving, 492
in the nature of a pair of laterally extending tapered lobate
depressions, cavities, or reliefs 494, 496 separated by a central bridge
region 498 having a deeper section and flanks that taper into reliefs
494, 496. Reliefs 494, 496 may have a major axis that runs laterally with
respect to the bearing adapter itself, but, as installed, runs axially
with respect to the axis of rotation of the underlying bearing. The
absence of material at reliefs 494, 496 may tend to leave a generally
H-shaped footprint on the circumferential surface 500 that seats upon the
outside of bearing 46, in which the two side regions, or legs, of the H
form lands or pads 502, 504 joined by a relatively narrow waist, namely
bridge region 498. To the extent that the undersurface of the lower
portion of bearing adapter 452 conforms to an arcuate profile, such as
may accommodate the bearing casing, reliefs 494, 496 may tend to run, or
extend, predominantly along the apex of the profile, between the pads, or
lands, that lie to either side. This configuration may tend to spread the
rocker rolling contact point load into pads 502, 504 and thence into
bearing 46. Bearing life may be a function of peak load in the rollers.
By leaving a space between the underside of the bearing adapter and the
top center of the bearing casing over the bearing races, reliefs 494, 496
may tend to prevent the vertical load being passed in a concentrated
manner predominantly into the top rollers in the bearing. Instead, it may
be advantageous to spread the load between several rollers in each race.
This may tend to be encouraged by employing spaced apart pads or lands,
such as pads 502, 504, that seat upon the bearing casing. Central bridge
region 498 may seat above a section of the bearing casing under which
there is no race, rather than directly over one of the races. Bridge
region 498 may act as a central circumferential ligature, or tension
member, intermediate bearing adapter end arches 506, 508 such as may tend
to discourage splaying or separation of pads 502, 504 away from each
other as vertical load is applied.

[0329]FIGS. 12a-12d

[0330]FIGS. 12a to 12d show an alternate assembly to that of FIG. 11a,
indicated generally as 510 for seating in a sideframe 512. Bearing 46 and
bearing adapter 452 may be as before. Assembly 510 may include an upper
rocker fitting identified as pedestal seat member 514, and resilient
members 516. Sideframe 512 may be such that the upper rocker fitting,
namely pedestal seat member 514 may have a greater through thickness, t,
than otherwise. This thickness, ts may be greater than 10% of the
magnitude of the width Ws of the pedestal seat member, and may be about
20 (+/-5) % of the width. In one embodiment the thickness may be roughly
the same as the thickness of and `LC pad` such as may be obtained from
Lord Corporation. Such thickness may be greater than 7/16'', and such
thickness may be 1 inch (+/-1/8''). Pedestal seat member 514 may tend to
have a greater thickness for enhancing the spreading of the rocker
contact load into sideframe 512. It may also be used as part of a
retro-fit installation in sideframes such as may formerly have been made
to accommodate LC pads.

[0331]Pedestal seat member 514 may have a generally planar body 518 having
upturned lateral margins 520 for bracketing, and seating about, the lower
edges of the sideframe pedestal roof member 522. The major portion of the
upper surface of body 518 may tend to mate in planar contact with the
downwardly facing surface of roof member 522. Seat member 514 may have
protruding end potions 524 that extend longitudinally from the main,
planar portion of body 518. End portions 524 may include a deeper nose
section 526, that may stand downwardly proud of two wings 528, 530. The
depth of nose section 526 may correspond to the general through thickness
depth of member 514. The lower, downwardly facing surface 532 of member
518 (as installed) may be formed to mate with the upper surface of the
bearing adapter, such that a bi-directional rocking interface is
achieved, with a combination of male and female rocking radii as
described herein. In one embodiment the female rocking surface may be
planar.

[0332]Resilient members 516 may be formed to engage protruding portions
524. That is, resilient member 516 may have the generally channel shaped
for of resilient member 156, having a lateral web 534 standing between a
pair of wings 536, 538. However, in this embodiment, web 534 may extend,
when installed, to a level below the level of stops 466, 468, and the
respective base faces 540, 542 of wings 536, 538 are positioned to sit
above stops 466, 468. A superior lateral wall, or bulge, 544 surmounts
the upper margin of web 534, and extends longitudinally, such as may
permit it to overhang the top of the sideframe jaw thrust lug 546. The
upper surface of bulge 544 may be trimmed, or flattened to accommodate
nose section 526. The upper extremities of wings 536, 538 terminate in
knobs, or prongs, or horns 548, 550 that stand upwardly proud of the
flattened surface 552 of bulge 544. As installed, the upper ends of horns
548, 550 underlie the downwardly facing surfaces of wings 536, 538.

[0333]In the event that an installer might attempt to install bearing
adapter 452 in sideframe 512 without first placing pedestal seat member
512 in position, the height of horns 548, 550 is sufficient to prevent
the rocker surface of bearing adapter 452 from engaging sideframe roof
member 522. That is, the height of the highest portion of the crown of
the rocker surface 552 of the bearing adapter is less than the height of
the ends of horns 548, 550 when horns 548, 550 are in contact with stops
466, 468. However, when pedestal seat member 512 is correctly in place,
nose section 526 is located between wings 536, 538, and wings 536, 538
are captured above horns 548, 550. In this way, resilient members 514,
and in particular horns 548, 550, act as installation error detection
elements, or damage prevention elements.

[0334]The steps of installation may include the step of removing an
existing bearing adapter, removing an existing elastomeric pad, such as
an LC pad, installing pedestal seat fitting 514 in engagement with roof
522; seating of resilient members 514 above each of thrust lugs 546; and
sliding bearing adapter 452 between resilient pad members 514. Resilient
pad members 514 then serve to locate other elements on assembly, to
retain those elements in service, and to provide a centering bias to the
mating rocker elements, as discussed above.

[0335]FIGS. 13a-13g

[0336]FIGS. 13a to 13g show and alternate bearing adapter 144 and pedestal
seat 146 pair. Bearing adapter 144 is substantially the same as bearing
adapter 44, except insofar as bearing adapter 44 has a fully curved top
surface 142, whereas bearing adapter 144 has an upper surface that has a
flat central portion 148 between somewhat elevated side portions 149. The
male bearing surface portion 147 is located centrally on flat central
portion 148, and extends upwardly therefrom. As with bearing adapter 44,
bearing adapter 144 has first and second radii r1 and r2, formed in the
longitudinal and transverse directions respectively, such that the
upwardly protruding surface so formed is a toroidal surface. Pedestal
seat 146 is substantially similar to pedestal seat fitting 38. Pedestal
seat 146 has a body having an upper surface 145 that seats in planar
abutment against the downwardly facing surface of pedestal roof 120, and
upwardly extending tangs 124 that engage lugs 122 as before.

[0337]While in the general sense, the female engagement fitting portion,
namely the hollow depression formed in the lower face of seat 146, is
formed on longitudinal and lateral radii R1 and R2, as above, when these
two radii are equal a spherical surface 143 is formed, giving the
circular plan view of FIG. 13a. FIGS. 13f and 13g serve to illustrate
that the male and female surfaces may be inverted, such that the female
engagement surface 560 is formed on bearing adapter 562, and the male
engagement surface 564 on seat 566.

[0338]FIGS. 14a-14e

[0339]FIGS. 14a-14e show enlarged views of bearing adapter 44 and pedestal
seat fitting 38. The compound curve of upwardly facing surface 142 runs
fully to terminate at the end faces 134, and the side faces 570 of
bearing adapter 44. The side faces show the circularly downwardly arched
lower walls margins 572 of side faces 570 that seat about bearings 46. In
all other respects, for the purposes of this description, bearing adapter
44 can be taken as being the same as bearing adapter 144.

[0340]FIGS. 15a-15c

[0341]FIGS. 15a-15c, show a conceptually similar bearing adapter and
pedestal seat combination to that of FIGS. 13a to 13g, but rather than
having the interface portions standing proud of the remainder of the
bearing adapter, the male portion 574 is sunken into the top of the
bearing adapter, and the surrounding surface 576 is raised up. The mating
female portion 578 while retaining its hollowed out shape, stands proud
of the surrounding structure of the seat to provide a corresponding
mating surface. The longitudinally extending phantom lines indicate drain
ports to discourage the collection of water.

[0342]FIGS. 16a-16e

[0343]Both female radii R1 and R2 need not be on the same
fitting, and both male radii r1 and r2 need not be on the same
fitting. In the saddle shaped fittings of FIGS. 16a to 16e, a bearing
adapter 580 is of substantially the same construction as bearing adapters
44 and 144, except insofar as bearing adapter 580 has an upper surface
592 that has a male fitting in the nature of a longitudinally extending
crown 582 with a laterally extending axis of rotation, for which the
radius of curvature is r1, and a female fitting in the nature of a
longitudinally extending trough 584 having a lateral radius of curvature
R2. Similarly, pedestal fitting 586 mounted in roof 120 has a
generally downwardly facing surface 594 that has a transversely extending
trough 588 having a longitudinally oriented radius of curvature R1,
for engagement with r1 of crown 582, and a longitudinally running,
downwardly protruding crown 590 having a transverse radius of curvature
r2 for engagement with R2 of trough 584. In FIGS. 16f and 16g
the saddle surfaces are inverted such that whereas bearing adapter 580
has r1 and R2, bearing adapter 596 has r2 and R1.
Similarly, whereas pedestal fitting 586 has r2 and R1, pedestal
fitting 598 has r1 and R2. In either case, the smallest of
R1 and R2 may be larger than, or equal to, the largest of
r1 and r2, and the mating opposed saddle surfaces, over the
desired range of motion, may tend to be torsionally decoupled as in
bearing adapters 44 and 144.

[0344]FIGS. 17a-17d

[0345]It may be desired that the vertical forces transmitted from the
pedestal roof into the bearing adapter be passed through line contact,
rather than the bi-directional rolling or rocking point contact. A
pedestal seat to bearing adapter interface assembly having line contact
rocker interfaces is represented by FIGS. 17a to 17d. A bearing adapter
600 has a hollowed out transverse cylindrical upper surface 602, acting
as a female engagement fitting portion formed on radius R1. Surface
602 may be a round cylindrical section, or it may be a parabolic, or
other cylindrical section.

[0346]The corresponding pedestal seat fitting 604 may have a
longitudinally extending female fitting, or trough, 606 having a
cylindrical surface 608 formed on radius r1. Again, fitting 604 is
cylindrical, and may be a round cylindrical section although,
alternatively, it could be parabolic, elliptic, or some other shape for
producing a rocking motion. Trapped between bearing adapter 600 and
pedestal seat fitting 604 is a rocker member 610. Rocker member 610 has a
first, or lower portion 612 having a protruding male cylindrical rocker
surface 614 formed on a radius r1 for line contact engagement of
surface 602 of bearing adapter 600 formed on radius R1, r1
being smaller than R1, and thus permitting longitudinal rocking to
obtain passive self steering. As above, the resistance to rocking, and
hence to self steering, may tend to be proportional to the weight on the
rocker and hence may give proportional self steering when the car is
either empty or loaded. Lower portion 612 also has an upper relief 616
that may be machined to a high level of flatness. Lower portion 612 also
has a centrally located, integrally formed upwardly extending cylindrical
stub 618 that stands perpendicularly proud of surface 616. A bushing 620,
which may be a press fit bushing, mounts on stub 618.

[0347]Rocker member 600 also has an upper portion 622 that has a second
protruding male cylindrical rocker surface 624 formed on a radius r2
for line contact engagement with the cylindrical surface 608 of trough
606, formed on radius R2, thus permitting lateral rocking of
sideframe 26. Upper portion 622 may have a lower relief 626 for placement
in opposition to relief 616. Upper portion 622 has a centrally located
blind bore 628 of a size for tight fitting engagement of bushing 620,
such that a close tolerance, pivoting connection is obtained that is
largely compliant to pivotal motion about the vertical, or z, axis of
upper portion 622 with respect to lower portion 612. That is to say, the
resistance to torsional motion about the z-axis is very small, and can be
taken as zero for the purposes of analysis. To aid in this, bearing 630
may be installed about stub 618 and bushing 620 and is placed between
opposed surfaces 606 and 616 to encourage relative rotational motion
therebetween.

[0348]In this embodiment, stub 618 could be formed in upper portion 622,
and bore 618 formed in lower portion 612, or, alternatively, bores 628
could be formed in both upper portion 612 and lower portion 622, and a
freely floating stub 618 and bushing 620 could be captured between them.
It may be noted that the angular displacement about the z axis of upper
portions 622 relative to lower portion 612 may be quite small--of the
order of 1 degree, and may tend not to be even that large overly
frequently.

[0349]Bearing adapter 600 may have longitudinally extending raised lateral
abutment side walls 632 to discourage lateral migration, or escape of
lower portion 612. Lower portion 612 may have non-galling, relatively low
co-efficient of friction side wear shim stock members 634 trapped between
the end faces of lower portion 612 and side walls 632. Bearing adapter
600 may also have a drain hole formed therein, possibly centrally, or
placed at an angle. Similarly, pedestal seat fitting 604 may have
laterally extending depending end abutment walls 636 to discourage
longitudinal migration, or escape, of upper portion 622. In a like manner
to shim stock members 634, non-galling, relatively low co-efficient of
friction end wear shim stock members 638 may be mounted between the end
faces of upper portion 622 and end abutment walls 636.

[0350]In an alternative to the foregoing embodiment, the longitudinal
cylindrical trough could be formed on the bearing adapter, and the
lateral cylindrical trough could be formed in the pedestal seat, with
corresponding changes in the entrapped rocker element. Further, it is not
necessary that the male cylindrical portions be part of the entrapped
rocker element. Rather, one of those male portions could be on the
bearing adapter, and one of those male portions could be on the pedestal
seat, with the corresponding female portions being formed on the
entrapped rocker element. In the further alternative, the rocker element
could include one male element, and one female element, having the male
element formed on r1 (or r2) being located on the bearing
adapter, and the female element formed on R1 (or R2) being on
the underside of the entrapped rocker element, and the male element
formed on r2 (or r1) being formed on the upper surface of the
entrapped rocker element, and the respective mating female element formed
on radius R2 (or R1) being formed on the lower face of the
pedestal seat. In the still further alternative, the rocker element could
include one male element, and one female element, having the male element
formed on r1 (or r2) being located on the pedestal seat, and
the female element formed on R1 (or R2) being on the upper
surface of the entrapped rocker element, and the male element formed on
r2 (or r1) being formed on the lower surface of the entrapped
rocker element, and the respective mating female element formed on radius
R2 (or R1) being formed on the upper face of the bearing
adapter. There are, in this regard, at least eight combinations as
represented in FIG. 17e by assemblies 601, 603, 605, 607, 611, 613, 615,
and 617.

[0351]The embodiment of FIGS. 17a-17d may tend to yield line contact at
the force transfer interfaces, and yet rock in both the longitudinal and
lateral directions, with compliance to torsion about the vertical axis.
That is, the bearing adapter to pedestal seat interface assembly may tend
to permit rotation about the longitudinal axis to give lateral rocking
motion of the side frame; rotation about a transverse axis to give
longitudinal rocking motion; and compliance to torsion about the vertical
axis. It may tend to discourage lateral translation, and may tend to
retain high stiffness in the vertical direction.

[0352]FIGS. 18a and 18b

[0353]The embodiment of FIGS. 18a and 18b is substantially similar to the
embodiment of FIGS. 17a to 17d. However, rather than employing a pivot
connection such as the bore, stub, bushing and bearing of FIGS. 17a-17d,
a rocker element 644 is captured between bearing adapter 600 and pedestal
seat 604. Rocker element 644 has a torsional compliance element made of a
resilient material, identified as elastomeric member 646 bonded between
the opposed faces of the upper 647 and lower 645 portions of rocker
element 644. Although FIGS. 18a and 18b show the laterally extending
trough in bearing adapter 600, and the longitudinal trough in pedestal
seat 604, the same permutations of FIG. 7e may be made. In general, while
the torsional element may be between the two cylindrical elements in a
manner tending torsionally to decouple them, it may be that the
elastomeric pad need not necessarily be installed between the two
cylindrical members. For example, the rocker element 644 may be solid,
and an elastomeric element may be installed beneath the top surface of
bearing adapter 600, or above the pedestal seat element, such that a
torsionally compliant element is placed in series with the two rockers.

[0354]The same general commentary may be made with regard to the pivotal
connection suggested above in connection with the example of FIGS. 17a to
17d. That is, the top of the bearing adapter could be pivotally mounted
to the body of the bearing adapter more generally, or the pedestal seat
could be pivotally mounted to the pedestal roof, such that a torsionally
compliant element would be in series with the two rockers. However, as
noted above, the torsionally compliant element may be between the two
rockers, such that they may tend to be torsionally de-coupled from each
other. In general, with regard to the embodiments of FIGS. 17a-17d, and
18a-18b, provided that the radii employed yield a physically appropriate
combination tending toward a local stable minimum energy state, the male
portion of the bearing adapter to pedestal seat interface (with the
smaller radius of curvature) may be on either the bearing adapter or on
the pedestal seat, and the mating female portion (with the larger radius
of curvature) may be on the other part, whichever it may be. In that
light, although a particular depiction may show a male portion on a
bearing adapter, and a female fitting on the pedestal seat, these
features may, in general, be reversed.

[0355]FIGS. 19a to 19c, 20a to 20c, and 21a to 21g

[0356]FIGS. 19a to 19c show the combination of a bearing adapter 650 with
an elastomeric bearing adapter pad 652 and a rocker 654 and pedestal seat
656 to permit lateral rocking of the sideframe. Bearing adapter 650,
shown in three additional views in FIGS. 20a-20c is substantially similar
to bearing adapter 44 (or 144) to the extent of its geometric features
for engaging a bearing, but differs therefrom in having a more or less
conventional upper surface. Upper surface 658 may be flat, or may have a
large (roughly 60'') radius crown 660, such as might have been used for
engaging a planar pedestal seat surface. Crown 660 is split into two
fore-and-aft portions, with a laterally extending central flat portion
between them. Abreast of the central flat portion, bearing adapter 650
has a pair of laterally proud, outwardly facing lateral lands, 662 and
664, and, amidst those lands, lateral lugs 666 that extend further still
proud beyond lands 662 and 664.

[0357]Bearing adapter pad 652 may be a commercially available assembly
such as may be manufactured by Lord Corporation of Erie Pa., or such as
may be identified as Standard Car Truck Part Number SCT 5844. Bearing
adapter pad 652 has a bearing adapter engagement member in the nature of
a lower plate 668 whose bottom surface 670 is relieved to seat over crown
660 in non-rocking engagement. Lateral and longitudinal translation of
bearing adapter pad 652 is inhibited by an array of downwardly bent
securement locating lugs, or fingers, or claws, in the nature of indexing
members or tangs 672, two per side in pairs located to reach downwardly
and bracket lugs 666 in close fitting engagement. The bracketing
condition with respect to lugs 666 inhibits longitudinal motion between
bearing adapter pad 652 and bearing adapter 650. The laterally inside
faces of tangs 672 closely oppose the laterally outwardly facing surfaces
of lands 662 and 664, tending thereby to inhibit lateral relative motion
of bearing adapter pad 652 relative to bearing adapter 650. The vertical,
lateral, and longitudinal position relative to bearing adapter 650 can be
taken as fixed.

[0358]Bearing adapter pad 652 also has an upper plate, 674, that, in the
case of a retro-fit installation of rocker 654 and seat 656, may have
been used as a pedestal seat engagement member. In any case, upper plate
674 has the general shape of a longitudinally extending channel member,
with a central, or back, portion, 676 and upwardly extending left and
right hand leg portions 678, 680 adjoining the lateral margins of back
portion 676. Leg portions 678 may have a size and shape such as might
have been suitable for mounting directly to the sideframe pedestal.

[0359]Between lower plate 668 and upper plate 674, bearing adapter pad 652
has a bonded resilient sandwich 680 that may include a first resilient
layer, indicated as lower elastomeric layer 682 mounted directly to the
upper surface of lower plate 668, an intermediate stiffener shear plate
684 bonded or molded to the upper surface of layer 682, and an upper
resilient layer, indicated as upper elastomeric layer 686 bonded atop
plate 684. The upper surface of layer 686 may be bonded or molded to the
lower surface of upper plate 674. Given that the resilient layers may be
quite thin as compared to their length and breadth, the resultant
sandwich may tend to have comparatively high vertical stiffness,
comparatively high resistance to torsion about the longitudinal (x) and
lateral (y) axes, comparatively low resistance to torsion about the
vertical (z) axis (given the small angular displacements in any case),
and non-trivial, roughly equal resistance to shear in the x or y
directions that may be in the range of 20,000 to 40,000 lbs per inch, or
more narrowly, about 30,000 lbs per inch for small deflections. Bearing
adapter pad 652 may tend to permit a measure of self steering to be
obtained when the elastomeric elements are subjected to longitudinal
shear forces.

[0360]Rocker 654 (seen in additional views 21e, 21f and 21g) has a body of
substantially constant cross-section, having a lower surface 690 formed
to sit in substantially flat, non-rocking engagement upon the upper
surface of plate 674 of bearing adapter pad 652, and an upper surface 692
formed to define a male rocker surface. Upper surface 692 may have a
continuously radius central portion 694 lying between adjacent tangential
portions 696 lying at a constant slope angle. In one embodiment, the
central portion may describe 4-6 degrees of arc to either side of a
central position, and may, in one embodiment have about 41/2 to 5
degrees. In the terminology used above, this radius is "r2", the
male radius of a lateral rocker for permitting lateral swinging motion of
side frame 26. Where a bearing adapter with a crown radius is mounted
under the resilient bearing adapter pad, the radius of rocker 654 is less
than the radius of the crown, perhaps less than half the crown radius,
and possibly being less than 1/3 of the crown radius. It may be formed on
a radius of between 5 and 20 inches, or, more narrowly, on a radius of
between 8 and 15 inches. Surface 692 could also be formed on a parabolic
profile, an elliptic or hyperbolic profile, or some other profile to
yield lateral rocking.

[0361]Pedestal seat 656 (seen in FIGS. 21a to 21d) has a body having a
major portion 700 that is substantially rectangular in plan view. When
viewed from one end in the longitudinal direction, pedestal seat 656 has
a generally channel shaped cross-section, in which major portion 700
forms the back 702 and two longitudinally running legs 704, 706 extend
upwardly and laterally outwardly from the lateral margins of major
portion 700. Legs 704 and 706 have an inner, or proximal portion 708 that
extends upwardly and outwardly at an angle from the lateral margins of
main portion 700, and an outer, or distal portion, or toe 710 that
extends from the end of proximal portion 708 in a substantially vertical
direction. The breadth between the opposed fingers of the channel section
(i.e., between opposed toes 710) corresponds to the width of the
sideframe pedestal roof 712, as shown in the cross-section of FIG. 19b,
with which legs 704 and 706 sit in close fitting, bracketing engagement.
Legs 704 and 706 have longitudinally centrally located cut-outs, reliefs,
rebates, or indexing features, identified as notches 714. Notches 714
seat in close fitting engagement about T-shaped lugs 716 (FIG. 19b) that
are welded to the sideframe on either side of the pedestal roof. This
engagement establishes the lateral and longitudinal position of pedestal
seat 656 with respect to sideframe 26.

[0362]Pedestal seat 656 also has four laterally projecting corner lugs, or
abutment fittings 718, whose longitudinally inwardly facing surfaces
oppose the laterally extending end-face surfaces of the upturned legs 678
of upper plate 674 of bearing adapter pad 652. That is, the corner
abutment fittings 718 on either lateral side of pedestal seat 656 bracket
the ends of the upturned legs 678 of adapter pad 652 in close fitting
engagement. This relationship fixes the longitudinal position of pedestal
seat 656 relative to the upper plate of bearing adapter pad 652.

[0363]Major portion 700 of pedestal seat 656 has a downwardly facing
surface 700 that is hollowed out to form a depression defining a female
rocking engagement surface 702. This surface is formed on a female radius
(identified as R2 in concordance with terminology used herein above)
that is quite substantially larger than the radius of central portion 694
(FIG. 21f) of rocker 654, such that rocker 654 and pedestal seat 656 meet
in rolling line contact engagement and permit sideframe 26 to swing
laterally in a lateral rocking relationship on rocker 654. The arcuate
profile of female rocking engagement surface 702 may be such as to
encourage lateral self centering of rocker 654, and may have a radius of
curvature that varies from a central region to adjacent regions, which
may be tangential planar regions. Where pedestal seat 656 and rocker 654
are provided by way of retro-fit installation above an adapter having a
crown radius, the radius of curvature of the pedestal seat may tend to be
less than or equal to the crown radius. The central radius of curvature
R2 of surface 702, or the radius of curvature generally if constant,
may be in the range of 6 to 60 inches, is preferably greater than 10
inches and less than 40 inches. It may be between 1 1/10 to 4 times as
large as the rocker radius of curvature r2. As noted elsewhere, the
pedestal seat need not have the female rocker surface, and the rocker
need not have the male rocker surface, but rather, these surfaces could
be reversed, so that the male surface is on the pedestal seat, and the
female surface is on the rocker. Particularly in the context of a
retro-fit installation, there may be relatively little clearance between
the upturned legs 678 of upper plate 674 and legs 704, 706 of pedestal
seat 656. This distance is shown in FIG. 19b as gap `G`, which is
preferably sufficient allowance for rocking motion between the parts that
rocking motion is bounded by the spacing of the truck bolster gibs 106,
108.

[0364]By providing the combination of a lateral rocker and a shear pad,
the resultant assembly may provide a generally increased softness in the
lateral direction, while permitting a measure of self steering. The
example of FIG. 19a may be provided as an original installation, or may
be provided as a retrofit installation. In the case of a retrofit
installation, rocker 654 and pedestal seat 656 may be installed between
an existing elastomeric pad and an existing pedestal seat, or may be
installed in addition to a replacement elastomeric pad of lesser
through-thickness, such that the overall height of the bearing adapter to
pedestal seat interface may remain roughly the same as it was before the
retrofit.

[0365]FIGS. 19e and 19f represent alternate embodiments of combinations of
elastomeric pads and rockers. While the embodiment of FIG. 19a showed an
elastomeric sandwich that had roughly equivalent response to shear in the
lateral and longitudinal directions, this need not be the general case.
For example, in the embodiments of FIGS. 19e and 19f, elastomeric bearing
adapter pad assemblies 720 and 731 have respective resilient elastomeric
laminates sandwiches, indicated generally as 722 and 723 in which the
stiffeners 726, 727 have longitudinally extending corrugations, or waves.
In the longitudinal direction, the sandwich may tend to react in nearly
pure shear, as before in the example of FIG. 19a. However, deflection in
the lateral direction now requires not only a shear component, but also a
component normal to the elastomeric elements, in compressive or tensile
stress, rather than, and in addition to, shear. This may tend to give a
stiffer lateral response, and hence an anisotropic response. An
anisotropic shear pad arrangement of this nature might have been used in
the embodiment of FIG. 19a, and a planar arrangement, as in the
embodiment of FIG. 19a could be used in either of the embodiments of
FIGS. 19e, and 19f. Considering FIG. 19e, both base plate 728 and upper
plate 730 have a wavy contour corresponding to the wavy contour of
sandwich 722 generally. Rocker 732 has a lower surface of corresponding
profile. Otherwise, this embodiment is substantially the same as the
embodiment of FIG. 19a.

[0366]Considering FIG. 19f, an elastomeric bearing adapter pad assembly
721 has a base plate 734 having a lower surface for seating in
non-rocking relationship on a bearing adapter, in the same manner as
bearing adapter pad assembly 652 sits upon bearing adapter 650. The upper
surface 735 of base plate 734 has a corrugated or wavy contour, the
corrugations running lengthwise, as discussed above. An elastomeric
laminate of a first resilient layer 736, an internal stiffener plate 737,
and a second resilient layer 738 are located between base plate 734 and a
correspondingly wavy undersurface of upper plate 740. Rather than being a
flat plate upon which a further rocker plate is mounted, upper plate 740
has an upper surface 742 having an integrally formed rocker contour
corresponding to that of the upper surface of rocker 654. Pedestal seat
744 then mounts directly to, and in lateral rocking relationship with
upper plate 740, without need for a separate rocker part. The combination
of bearing adapter pad 721 and pedestal seat 742 may have interconnecting
abutments 747 to prevent longitudinal migration of rocker surface 742
relative to the contoured downwardly facing surface 748 of pedestal seat
744.

[0367]FIGS. 22a to 22c, 23a and 23b

[0368]Rather than employ a bearing adapter that is separate from the
bearing, FIGS. 22a to 22c show a bearing 750 mounted on one of the end of
an axle 752. Bearing 750 has an integrally formed arcuate rolling contact
surface 754 for mating rolling point contact with a mating rolling
contact surface 756 of a pedestal seat fitting 758. The general geometry
of the rolling relationship is as described below in terms of the
possible relationships of r1, R1 and L, and, as noted above, the male and
female rolling contact surfaces can be reversed, such that the male
surface is on the pedestal seat, and the female surface is on the
bearing, or further still, in the case of a compound curvature, the
surfaces made be saddle shaped, as described above. The bearing
illustrations of FIGS. 22b and 23b are based on the bearing cross-section
illustration shown on page 812 of the 1997 Car and Locomotive Cyclopedia.
That illustration was provided to the Cyclopedia courtesy of Brenco Inc.,
of Petersburg, Va.

[0369]In greater detail, bearing 750 is an assembly of parts including an
inner ring 760, a pair of tapered roller assemblies 762 whose inner ring
engages axle 752, and an outer ring member 764 whose inner frustoconical
bearing surfaces engage the rollers of assemblies 762. The entire
assembly, including seals, spacers, and backing ring is held in place by
an end cap 766 mounted to the end of axle 752. In the assembly of FIGS.
22a to 22c, does not employ a round cylindrical outer ring member, but
rather, ring member 764 is made with an upper portion 770 having the same
general shape and function as bearing adapter 44 or 144, including
tapered end walls 768 for rocking motion travel limiting abutment against
the surfaces of the pedestal jaws 130 as described above. Further, upper
portion 770 includes corner abutments 774 for bracketing jaws 130, again,
as described above. Thus a bearing is provided with an integrally formed
rocking surface. The rocking surface is permanently fixed with relation
to the remainder of the underlying bearing assembly. In this way, an
assembly is provided in which rotation of the bearing housing is
inhibited relative to the rocking surface.

[0370]In FIGS. 23a and 23b, an integrated bearing and bearing adapter
rocker assembly, or wheelset to pedestal interface assembly, is indicated
as modified bearing 790. In this case the outer ring 792 has been formed
in the shape of a laterally extending, cylindrical rocker surface 794,
such as a male surface (although it could be female as discussed above),
for engaging the mating female (although, as discussed, it could be male)
laterally rocker surface 796 of pedestal seat 798, such as may tend to
provide weight-proportional self steering, as discussed above.

[0371]Thus, the embodiments of FIGS. 22a and 23a both show a sideframe
pedestal to axle bearing interface assembly for a three piece rail road
car truck. The assembly of the embodiment of FIG. 22a has fittings that
are operable to rock both laterally and longitudinally. Both embodiments
include bearing assemblies having one of the rocking surface fittings,
whether male or female, of saddle shape, formed as an integral portion of
the outer ring of the bearing, such that the location of the rolling
contact surface is rigidly located relative to the bearing (because, in
this instance, it is part of the bearing). In the embodiment of FIG. 22a,
the integrally firmed surface is a compound surface, whereas in the
embodiment of FIG. 23b, the rolling contact surface is a cylindrical
surface, which may be formed on an arc of constant radius of curvature.

[0372]The possible permutations of surface types include those indicated
above in terms of a two element interface (i.e., the rocking surface on
the top of the bearing, and the mating rocking surface on the pedestal
seat) or a three element interface, in which an intermediate rocking
member is mounted between (a) the surface rigidly located with respect to
the bearing races, and (b) the surface of the pedestal seat. As above,
one or another of the surfaces may be formed on a spherical arc portion
such that the fittings are torsionally compliant, or, put alternatively,
torsionally de-coupled with respect to rotation about the vertical axis.
The permutations may also include the use of resilient pads such as
members 156, 374, 412, or 456, as may be appropriate.

[0373]Each of the assemblies of FIGS. 22a and 23a has a bearing for
mounting to one end of an axle of a wheelset of a three-piece railroad
car truck. The bearing has an outer member mounted in a position to
permit the end of the axle to rotate relative thereto, inasmuch as the
inner ring is intended to rotate with respect to the outer ring. The
bearing has an axis of rotation, about which its rings and bearings are
concentric that, when installed, may tend to be coincident with the
longitudinal axis of the axis of the axle of the wheelset. In each case,
the outer member has a rocking surface formed thereon for engaging a
mating rolling contact surface of a pedestal seat member of a sideframe
of the three piece truck.

[0374]The rolling contact surface of the bearing has a local minimum
energy condition when centered under the corresponding seat, and it is
preferred that the mating rolling contact surface be given a radius that
may tend to encourage self centering of the male rolling contact element.
That is to say, displacement from the minimum energy position (preferably
the centered position) may tend to cause the vertical separation distance
between the centerline of the wheelset axis (and hence the centerline of
the axis of rotation of the bearing) to become more distantly spaced from
the sideframe pedestal roof, since the rocking action may tend marginally
to raise the end of the sideframe, thus increasing the stored potential
energy in the system.

[0375]This can be expressed differently. In cylindrical polar
co-ordinates, the long axis of the wheelset axle may be considered as the
axial direction. There is a radial direction measured perpendicularly
away from the axial direction, and there is an angular circumferential
direction that is mutually perpendicular to both the axial direction, and
the radial direction. There is a location on the rolling contact surface
that is closer to the axis of rotation of the bearing than any other
location. This defines the "rest" or local minimum potential energy
equilibrium position. Since the radius of curvature of the rolling
contact surface is greater than the radial length, L, between the axis of
rotation of the bearing and the location of minimum radius, the radial
distance, as a function of circumferential angle θ will increase to
either side of the location of minimum radius (or, put alternatively, the
location of minimum radial distance from the axis of rotation of the
bearing lies between regions of greater radial distance). Thus the slope
of the function r(θ), namely dr/dθ, is zero at the minimum
point, and is such that r increases at an angular displacement away from
the minimum point to either side of the location of minimum potential
energy. Where the surface has compound curvature, both dr/dθ and
dr/dL are zero at the minimum point, and are such that r increases to
either side of the location of minimum energy to all sides of the
location of minimum energy, and zero at that location. This may tend to
be true whether the rolling contact surface on the bearing is a male
surface or a female surface or a saddle, and whether the center of
curvature lies below the center of rotation of the bearing, or above the
rolling contact surfaces. The curvature of the rolling contact surface
may be spherical, ellipsoidal, toroidal, paraboloid, parabolic or
cylindrical. The rolling contact surface has a radius of curvature, or
radii of curvature, if a compound curvature is employed, that is, or are,
larger than the distance from the location of minimum distance from the
axis of rotation, and the rolling contact surfaces are not concentric
with the axis of rotation of the bearing.

[0376]Another way to express this is to note that there is a first
location on the rolling contact surface of the bearing that lies radially
closer to the axis of rotation of the bearing than any other location
thereon. A first distance, L is defined between the axis of rotation, and
that nearest location. The surface of the bearing and the surface of the
pedestal seat each have a radius of curvature and mate in a male and
female relationship, one radius of curvature being a male radius of
curvature r1, the other radius of curvature being a female radius of
curvature, R2, (whichever it may be). r1 is greater than L,
R2 is greater than r1, and L, r1 and R2 conform to
the formula L-1-(r1-1-R2-1)>0, the rocker
surfaces being co-operable to permit self steering.

[0377]FIGS. 24a to 24e

[0378]FIGS. 24a to 24e relate to a three piece truck 200. Truck 200 has
three major elements, those elements being a truck bolster 192, that is
symmetrical about the truck longitudinal centerline, and a pair of first
and second side frames, indicated as 194. Only one side frame is shown in
FIG. 14c given the symmetry of truck 200. Three piece truck 200 has a
resilient suspension (a primary suspension) provided by a spring group
195 trapped between each of the distal (i.e., transversely outboard) ends
of truck bolster 192 and side frames 194.

[0379]Truck bolster 192 is a rigid, fabricated beam having a first end for
engaging one side frame assembly and a second end for engaging the other
side frame assembly (both ends being indicated as 193). A center plate or
center bowl 190 is located at the truck center. An upper flange 188
extends between the two ends 194, being narrow at a central waist and
flaring to a wider transversely outboard termination at ends 194. Truck
bolster 192 also has a lower flange 189 and two fabricated webs 191
extending between upper flange 188 and lower flange 189 to form an
irregular, closed section box beam. Additional webs 197 are mounted
between the distal portions of flanges 188 and 189 where bolster 192
engages one of the spring groups 195. The transversely distal region of
truck bolster 192 also has friction damper seats 196, 198 for
accommodating friction damper wedges.

[0380]Side frame 194 may be a casting having pedestal fittings 40 into
which bearing adapters 44, bearings 46, and a pair of axles 48 and wheels
50 mount. Side frame 194 also has a compression member, or top chord
member 32, a tension member, or bottom chord member 34, and vertical side
columns 36 and 36, each lying to one side of a vertical transverse plane
bisecting truck 200 at the longitudinal station of the truck center. A
generally rectangular opening is defined by the co-operation of the upper
and lower beam members 32, 34 and vertical sideframe columns 36, into
which end 193 of truck bolster 192 can be introduced. The distal end of
truck bolster 192 can then move up and down relative to the side frame
within this opening. Lower beam member 34 has a bottom or lower spring
seat 52 upon which spring group 195 can seat. Similarly, an upper spring
seat 199 is provided by the underside of the distal portion of bolster
192 which engages the upper end of spring group 195. As such, vertical
movement of truck bolster 192 will tend to increase or decrease the
compression of the springs in spring group 195.

[0381]In the embodiment of FIG. 24a, spring group 195 has two rows of
springs 193, a transversely inboard row and a transversely outboard row.
In one embodiment each row may have four large (8 inch +/-) diameter coil
springs giving vertical bounce spring rate constant, k, for group 195 of
less than 10,000 lbs./inch. In one embodiment this spring rate constant
may be in the range of 6000 to 10,000 lbs./in., and may be in the range
of 7000 to 9500 lbs./in, giving an overall vertical bounce spring rate
for the truck of double these values, perhaps in the range of 14,000 to
18,500 lbs./in for the truck. The spring array may include nested coils
of outer springs, inner springs, and inner-inner springs depending on the
overall spring rate desired for the group, and the apportionment of that
stiffness. The number of springs, the number of inner and outer coils,
and the spring rate of the various springs can be varied. The spring
rates of the coils of the spring group add to give the spring rate
constant of the group, typically being suited for the loading for which
the truck is designed.

[0382]Each side frame assembly also has four friction damper wedges
arranged in first and second pairs of transversely inboard and
transversely outboard wedges 204, 205, 206 and 207 that engage the
sockets, or seats 196, 198 in a four-cornered arrangement. The corner
springs in spring group 195 bear upon a friction damper wedge 204, 205,
206 or 207. Each vertical column 36 has a friction wear plate 92 having
transversely inboard and transversely outboard regions against which the
friction faces of wedges 204, 205, 206 and 207 can bear, respectively.
Bolster gibs 106 and 108 lie inboard and outboard of wear plate 92
respectively.

[0383]In the illustration of FIG. 24e, the damper seats are shown as being
segregated by a partition 208. If a longitudinal vertical plane is drawn
through truck 200 through the center of partition 208, it can be seen
that the inboard dampers lie to one side of plane 209, and the outboard
dampers lie to the outboard side of the plane. In hunting then, the
normal force from the damper working against the hunting will tend to act
in a couple in which the force on the friction bearing surface of the
inboard pad will always be fully inboard of the plane on one end, and
fully outboard on the other diagonal friction face.

[0384]In one embodiment, the size of the spring group embodiment of FIG.
24b may yield a side frame window opening having a width between the
vertical columns 36 of side frame 194 of roughly 33 inches. This is
relatively large compared to existing spring groups, being more than 25%
greater in width. In the embodiment of FIG. 1f truck 20 may also have an
abnormally wide sideframe window to accommodate 5 coils each of 51/2''
dia. Truck 200 may have a correspondingly greater wheelbase length,
indicated as WB. WB may be greater than 73 inches, or, taken as a ratio
to the track gauge width, may be greater than 1.30 time the track gauge
width. It may be greater than 80 inches, or more than 1.4 times the gauge
width, and in one embodiment is greater than 1.5 times the track gauge
width, being as great, or greater than, about 84 inches. Similarly, the
side frame window may be wider than tall. The measurement across the wear
plate faces between the opposed side frame columns 36 may be greater than
24'', possibly in the ratio of greater than 8:7 of width to height, and
possibly in the range of 28'' or 32'' or more, giving ratios of greater
than 4:3 and greater than 3:2. The spring seat may have lengthened
dimensions to correspond to the width of the side frame window, and a
transverse width of 151/2-17'' or more.

[0385]FIGS. 25a to 25d

[0386]FIGS. 25a to 25d, show an alternate truck embodiment. Truck 800 has
a bolster 808, side frame 807 and damper 801, 802 installation that
employs constant force inboard and outboard, fore and aft pairs of
friction dampers 801, 802 independently sprung on horizontally acting
springs 803, 804 housed in side-by-side pockets 805, 806 mounted in the
ends of truck bolster 808. While only two dampers 801, 802 are shown, a
pair of such dampers faces toward each of the opposed side frame columns.
Dampers 801, 802 may each include a block 809 and a consumable wear
member 810 mounted to the face of block 809. The block and wear member
have mating male and female indexing features 812 to maintain their
relative position. A removable grub screw fitting 814 is provided in the
spring housing to permit the spring to be pre-loaded and held in place
during installation. Springs 803, 804 urge, or bias, friction dampers
801, 802 against the corresponding friction surfaces of the sideframe
columns. The deflection of springs 803, 804 does not depend on
compression of the main spring group 816, but rather is a function of an
initial pre-load.

[0387]FIGS. 26a and 26b

[0388]FIGS. 26a and 26b show a partial isometric view of a truck bolster
820 that is generally similar to truck bolster 402 of FIG. 14a, except
insofar as bolster pocket 822 does not have a central partition like web
452, but rather has a continuous bay extending across the width of the
underlying spring group, such as spring group 436. A single wide damper
wedge is indicated as 824. Damper 824 is of a width to be supported by,
and to be acted upon, by two springs 825, 826 of the underlying spring
group. In the event that bolster 400 may tend to deflect to a
non-perpendicular orientation relative to the associated side frame, as
in the parallelogramming phenomenon, one side of wedge 824 may tend to be
squeezed more tightly than the other, giving wedge 824 a tendency to
twist in the pocket about an axis of rotation perpendicular to the angled
face (i.e., the hypotenuse face) of the wedge. This twisting tendency may
also tend to cause differential compression in springs 825, 826, yielding
a restoring moment both to the twisting of wedge 824 and to the
non-square displacement of truck bolster 820 relative to the truck side
frame. There may tend to be a similar moment generated at the opposite
spring pair at the opposite side column of the side frame. FIG. 26b shows
an alternate pair of damper wedges 827, 828. This dual wedge
configuration can similarly seat in bolster pocket 822, and, in this
case, each wedge 827, 828 sits over a separate spring. Wedges 827, 828
are slidable relative to each other along the primary angle of the face
of bolster pocket 822. When the truck moves to an out of square
condition, differential displacement of wedges 827, 828 may tend to
result in differential compression of their associated springs, e.g.,
825, 826 resulting in a restoring moment. In either case, the bolster
pockets may have wear liners 494, and the pockets themselves may be part
of prefabricated inserts 506 to be welded to the end of the bolster,
either at original manufacture or retro-fit, such as might include
installation of wider sideframe columns, and a different spring group
selection such as might accompany a retrofit conversion from a single
damper to a double damper (i.e., four cornered) arrangement.

[0389]FIGS. 27a and 27b

[0390]FIG. 27a shows a bolster 830 that is similar to bolster 210 except
insofar as bolster pockets 831, 832 each accommodate a pair of split
wedges 833, 834. Pockets 831, 832 each have a pair of bearing surfaces
835, 836 that are inclined at both a primary angle α and a
secondary angle β, the secondary angles of surfaces 835 and 836
being of opposite hand to yield the damper separating forces discussed
above. Surfaces 835 and 836 are also provided with linings in the nature
of relatively low friction wear plates 837, 838. Each pair of split
wedges seats over a single spring.

[0391]The example of FIG. 27b shows a combination of a bolster 840 and
biased split wedges 841, 842. Bolster pockets 843, 844 are stepped
pockets in which the steps, e.g., items 845, 846, have the same primary
angle α, and the same secondary angle β, and are both biased
in the same direction, unlike the symmetrical faces of the split wedges
in FIG. 27a, which are left and right handed. Thus the outboard pair of
split wedges 842 has first and second members 847, 848 each having
primary angle α and secondary angle β of the same hand, both
members being biased in the outboard direction. Similarly, the inboard
pair of split wedges 841 has first and second members 849, 850 having
primary angle α, and secondary angle β, except that the sense
of secondary angle β is such that members 849 and 850 tend to be
driven in the inboard direction. In the arrangement of FIG. 27c a single
stepped wedge 851, 852 may be used in place of the pair of split wedges
e.g., members 847, 848 or 849, 850. A corresponding wedge of opposite
hand is used in the other bolster pocket.

[0392]FIGS. 28a and 28b

[0393]In FIG. 28a, a truck bolster 860 has welded bolster pocket inserts
861, 862 of opposite hands welded into accommodations in its end. Each
bolster pocket has inboard and outboard portions 863, 864 that share the
same primary angle α, but have secondary angles β that are of
opposite hand. Respective inboard and outboard wedges are indicated as
865, 866, each seating over a vertically oriented spring 867, 868. In
this case bolster 860 is similar to bolster 820 of FIG. 26a, to the
extent that there is no land separating the inner and outer portions of
the bolster pocket. Bolster 860 is also similar to bolster 210 of FIG. 5,
except that the bolster pockets of opposite hand are merged without an
intervening land. In FIG. 28b, split wedge pairs 869, 870 (inboard) and
871, 872 (outboard) are employed in place of the single inboard and
outboard wedges 865 and 866.

[0394]FIGS. 29a-29c

[0395]FIGS. 29a-29c illustrate an alternate embodiment of bolster gib and
sideframe inter-relationship, such as may be incorporated in a truck such
as truck 20, or 22, or other truck shown or described herein. In the
embodiment of FIGS. 29a-29c, truck 900 has a bolster 902 and sideframes
904. It may be that a type or railroad freight car, such as a coal car,
in which truck 900 might be employed, for example, may be operated in the
light car (i.e., empty) condition, as when being returned to a location
for loading once again with lading. Such a car, or string of such cars,
may be dragged or pushed in the empty condition on not necessarily the
best track, with relatively sharp curves. In such a condition, the
lateral forces imposed on the truck may be proportionately great relative
to the vertical force on the truck due to gravity acting on the car. The
ratio of these forces is sometimes referred to as the L/V ratio. In such
circumstances it may be appropriate to have a relatively small allowance
for lateral travel of the bolster relative to the sideframes. With a
fully laden car, however, the L/V ratio may be low, or lower, and a tight
bolster gib spacing may not yield the most desirable result with respect
to wear on the rails. A wider gib spacing for a fully laden car may
permit a larger lateral excursion before contact occurs between the
bolster gib and sideframe, and so may yield a more desirable overall ride
quality.

[0396]Truck 900 may have one of the sideframe to wheelset interface
assemblies of one or another of the embodiments described herein, which,
as noted, may include a lateral rocking fitting. Bolster 902 may have at
each end thereof, and on each fore and aft face thereof (being
symmetrical about its central axis and being symmetrical about its long
axis) an inboard bolster gib 906, and an outboard bolster gib 908.
Inboard bolster gib 906 may be mounted inboard of the most laterally
inboard portion of the bolster damper pockets 910, and outboard bolster
gib 908 may be mounted outboard of the most outboard portion of the
bolster pocket, 912, and may be mounted to the distal extremity of
bolster 902. Although truck 900 may have a four cornered damper, or
double damper, arrangement as in truck 20 or 22, a tapered gib
arrangement such as here described, may be employed with a single damper
installation, as in truck 250 of FIG. 1e.

[0397]Inboard gib 906 may have a body 914 extending generally
perpendicularly away from the front face web 916 of bolster 902, and may
have an abutment surface 918 facing toward the sideframe column 920, and,
more specifically, toward a stop identified as a sideframe column
abutment face 922 that lies on the laterally inboard margin of the
reinforced wear plate backing frame portion 924 of sideframe column 920.
When viewed in profile, (that is to say looking parallel to the long axis
of the sideframe), abutment surface 918 may be inclined, and may be
inclined linearly, such as at an angle gamma, y, from the vertical on a
slope that extends upward and inboard, downward and outboard. Similarly,
abutment face 922 may also be relieved at angle gamma y. As the vertical
deflection of the spring group 915 increases, the lateral translational
gap, i.e., the gap measured on the horizontal plane, of the light car
condition, indicated in FIG. 29c as `G1` as the horizontal distance
between surface 918 and surface 922, may also tend to increase such that
the clearance may differ for different at rest positions of the bolster
according to the amount of lading carried by the car as indicated by the
larger lateral dimension of the gap, indicated as `G2` in FIG. 29d.
The lateral translational gap `G2` may correspond to the gap size in
the at rest position of a fully laden car. `G2` and `G1` are
measures of allowance for lateral translation of the bolster relative to
the sideframe, and in some embodiments may be related to the vertical
spring displacement between two, G2=G1+δspring
tanγ. In the instance where the opposed surfaces are planar and
parallel, the gap width normal to the opposed surfaces are G2
Cosγ or Gi Cosγ respectively. In operation, lateral
translation of bolster 902 relative to sideframe 904 may tend to urge
surfaces 916 and 920 toward (or away) from each other, with the limit of
travel being reached when they abut. As may be appreciated, lateral
travel in one direction may cause abutting contact with the gib stop on
one sideframe, while lateral travel in the opposite direction may yield
abutting contact with the gib stop on the other sideframe such that the
lateral travel is bounded in both directions. The upper or lower, or
both, vertices of surface 918 may have relatively generous radii 925.

[0398]It may be that the at rest spacing `P` of the outboard bolster gib
may be comparable to, or slightly greater than, the at rest spacing of
the inboard gib from the stop on the sideframe at the fully laden
condition. That is, dimension `P` may be greater than dimension `G2`
when bolster 902 is in its at rest position in the fully laden condition.
In one embodiment, `P` may be in the range of 1 to 13/8 inches, and may
be about 11/4 inches. In one embodiment `G1` may be in the range of
3/8 to 5/8 inches, and may be about 1/2 inch in the light car condition,
and `G2` may be in the range of 1 inch to 11/4 inches in the fully
laden condition, and may be in the range of 11/4 to 11/2 inches, and may
be about 13/8 inches in the full travel "solid" condition of the spring
group. In some embodiments the outboard gib 908 may have a vertical,
planar abutment surface as illustrated in FIGS. 29a to 29d, and may serve
primarily to prevent escape of sideframe 904 from bolster 902. In other
embodiments outboard gib 908 may also have a tapered abutment contact
surface 926 as illustrated in FIG. 29e in the manner of gib 906, and the
outboard abutment surface or stop 928 of sideframe column 920 may also be
tapered.

[0399]Angle gamma, γ, may lie in the range of about tan-1 (1 1/16)
to tan-1 ( 2/16), or, alternatively, about 5 degrees to about 40 degrees,
and in one embodiment the incremental slope relating increased lateral
spacing to increased at rest deflection of the main spring groups may be
about 7/16 inches of additional travel per inch of additional vertical
deflection, (+/-25%).

[0400]Although the embodiments of FIGS. 29a-29d may employ gibs and
mating, co-operation stops of identical profiles, being mating positive
and negative images such as surfaces 918 and 922, this need not
necessarily be so. In another embodiment, as shown in FIG. 29f, an
abutment may have a non-straight edge form, as indicated by arcuate
surface 930, which may follow a circular or parabolic arc for contact
with a mating face, such as linear face 932. The arc may have a local
radius of curvature Ro. The arcuate surface 930 may be formed such that
the point of tangency (when abutting the stop) is at the mid point of the
arc. It may also be understood that the arcuate surface is formed on the
sideframe column, while the other surface could be formed on the gib,
i.e., the relationship could be reversed.

[0401]FIGS. 30a-30g

[0402]An alternate form of damper assembly 940 is illustrated in FIGS. 30a
to 30g. Damper assembly 940 may include a wedge body 942 and a friction
member 944 matingly engageable with body 942. In this instance, friction
member 944 may be a replaceable member that seats in a forwardly facing
socket 946 formed in body 942. Although socket 946 may have a female
form, and friction member 944 may have a corresponding male form, this
could be reversed, with the illustrations of FIGS. 30a to 30g being
intended to be generically representative in this regard, without the
need for duplication of the drawings in the reversed male and female
roles. Friction member 944 may have a rearwardly protruding bulge having
an engagement interface surface 948 that is formed on a body of
revolution, and that may have a compound curvature with radii of
curvature about both an horizontal axis `y` and a vertical axis `z`.
Socket 946 may have a mating engagement interface surface 950 of
complementary compound curvature. Furthermore, either or both of surfaces
948 and 950 may be treated to reduce friction therebetween, as by
applying a polymeric or other sliding surface layer or treatment. A
lubricant, which may be a solid lubricant, may be used between surfaces
948 and 950 as may a coating, such as an anti-galling coating.

[0403]To the extent that the bolster may flex to a non-square condition
with respect to the sideframe columns, or to the extent that there may be
a relative rise or fall between the leading and trailing wheels of the
sideframe such that the sideframe rotates about the long axis of the
truck bolster, friction member 944 may tend to be urged to pitch or yaw
relative to the bolster, while maintaining friction face 952 in planar
contact with the opposing sideframe column wear plate. The use of mating
curvatures on surfaces 948 and 950, which may be mating spherical
curvatures, may give degrees of freedom of rotation about the `y` and `z`
axes to accommodate a measure of angular displacement of friction member
944 relative to body 942 under those pitch and yaw conditions. The
hypotenuse face 954 of body 942 may be planar (that is, it may lack the
crown discussed hereinabove), and may have primary and secondary angles
as discussed above. The base, or spring seat socket side 960 of body 942
may be as above, and may have a skirt, or skirt array of depending
members 961, 962, 963 for capturing the upper end of a spring, such as
indicated as 938. Friction member 944 may be formed of a compound having
known friction properties friction properties throughout, or may have a
back portion 956 for seating against body 942, and a front portion, or
friction face portion 958 as it may be termed, that may be a layer or pad
having known friction properties such as those types of coatings, or
surfaces or pads described elsewhere herein. The front and back portions
958, 956 may be releaseably engageable, or releaseably mutually
interlocking, or, alternatively, may be cast or bonded together in a
permanent or substantially permanent manner. Body 942 may also have
spaced apart, parallel planar side faces 964, 966, that may slide in
planar relationship against an end face of the corresponding bolster
pocket. While face portion 958 may have a circular friction face 952, it
could also be extended to have a non-circular face, such as generally
square or rectangular contact footprint against the sideframe column wear
plate, such as when the compound curvature has different radii of
curvature about the z any y axes. In use, when the friction compound, for
example, portion 958, has been worn away in large measure, be it 1/2,
2/3, 3/4 of the original material being worn away, or some other wear
criteria having been surpassed, then friction member 944 may be extracted
during servicing and a new or re-built friction member 944 may be
installed instead.

[0404]Compound Pendulum Geometry

[0405]The various rockers shown and described herein may employ rocking
elements that define compound pendulums--that is, pendulums for which the
male rocker radius is non-zero, and there is an assumption of rolling (as
opposed to sliding) engagement with the female rocker. The embodiment of
FIG. 2a (and others) for example, shows a bi-directional compound
pendulum. The performance of these pendulums may affect both lateral
stiffness and self-steering on the longitudinal rocker.

[0406]The lateral stiffness of the suspension may tend to reflect the
stiffness of (a) the sideframe between (i) the bearing adapter and (ii)
the bottom spring seat (that is, the sideframes swing laterally); (b) the
lateral deflection of the springs between (i) the lower spring seat and
(ii) the upper spring seat mounting against the truck bolster, and (c)
the moment between (i) the spring seat in the sideframe and (ii) the
upper spring mounting against the truck bolster. The lateral stiffness of
the spring groups may be approximately 1/2 of the vertical spring
stiffness. For a 100 or 110 Ton truck designed for 263,000 or 286,000 lbs
GRL, vertical spring group stiffness might be 25-30,000 lbs./in.,
assuming two groups per truck, and two trucks per car, giving a lateral
spring stiffness of 13-16,000 lbs./in. The second component of stiffness
relates to the lateral rocking deflection of the sideframe. The height
between the bottom spring seat and the crown of the bearing adapter might
be about 15 inches (+/-). The pedestal seat may have a flat surface in
line contact on a 60 inch radius bearing adapter crown. For a loaded
286,000 lbs. car, the apparent stiffness of the sideframe due to this
second component may be 18,000-25,000 lbs./in, measured at the bottom
spring seat. Stiffness due to the third component, unequal compression of
the springs, is additive to sideframe stiffness.

[0407]An alternate truck is the "Swing Motion" truck, such as shown at
page 716 in the 1980 Car and Locomotive Cyclopedia (1980,
Simmons-Boardman, Omaha). In a swing motion truck, the sideframe may act
more like a pendulum. The bearing adapter may have a female rocker, of
perhaps 10 in. radius. A mating male rocker mounted in the pedestal roof
may have a radius of perhaps 5 in. Depending on the geometry, this may
yield a sideframe resistance to lateral deflection in the order of 1/4
(or less) to about 1/2 of what might otherwise be typical. If combined
with the spring group stiffness, the relative softness of the pendulum
may be dominant. Lateral stiffness may then be less governed by vertical
spring stiffness. Use of a rocking lower spring seat may reduce, or
eliminate, lateral stiffness due to unequal spring compression. Swing
motion trucks have used transoms to link the side frames, and to lock
them against non-square deformation. Other substantially rigid truck
stiffening devices such as lateral unsprung rods or a "frame brace" of
diagonal unsprung bracing have been used. Lateral unsprung bracing may
increase resistance to rotation of the sideframes about the long axis of
the truck bolster. This may not necessarily enhance wheel load
equalization or discourage wheel lift.

[0408]A formula may be used for estimation of truck lateral stiffness:

ktruck=2×[(ksideframe)-1+(kspring shear)]-1

[0409]where [0410]ksideframe=[kpendulum+kspring moment]
[0411]kspring shear=The lateral spring constant for the spring group
in shear. [0412]kpendulum=The force required to deflect the pendulum
per unit of deflection, as measured at the center of the bottom spring
seat.

[0413]kspring moment=The force required to deflect the bottom spring
seat per unit of sideways deflection against the twisting moment caused
by the unequal compression of the inboard and outboard springs.

[0414]In a pendulum, the relationship of weight and deflection is roughly
linear for small angles, analogous to F=kx, in a spring. A lateral
constant can be defined as kpendulum=W/L, where W is weight, and L
is pendulum length. An approximate equivalent pendulum length can be
defined as Leq=W/kpendulum. W is the sprung weight on the
sideframe. For a truck having L=15 and a 60'' crown radius, Leq
might be about 3 in. For a swing motion truck, Leq may be more than
double this.

[0415]A formula for a longitudinal (i.e., self-steering) rocker as in FIG.
2a, may also be defined:

F/δlong=klong=(W/L)[[(1/L)/(1/r1-1/R1)]-1]

[0416]Where:

[0417]klong is the longitudinal constant of proportionality between
longitudinal force and longitudinal deflection for the rocker.

[0418]F is a unit of longitudinal force, applied at the centerline of the
axle

[0419]δlong is a unit of longitudinal deflection of the
centerline of the axle

[0420]L is the distance from the centerline of the axle to the apex of
male portion 116.

[0421]R1 is the longitudinal radius of curvature of the female hollow
in the pedestal seat 38.

[0422]r1 is the longitudinal radius of curvature of the crown of the
male portion 116 on the bearing adapter

[0423]In this relationship, R1 is greater than r1, and (1/L) is
greater than [(1/r1)-(1/R1)], and, as shown in the
illustrations, L is smaller than either r1 or R1. In some embodiments
herein, the length L from the center of the axle to apex of the surface
of the bearing adapter, at the central rest position may typically be
about 53/4 to 6 inches (+/-), and may be in the range of 5-7 inches.
Bearing adapters, pedestals, side frames, and bolsters are typically made
from steel. The present inventor is of the view that the rolling contact
surface may preferably be made of a tool steel, or a similar material.

[0424]In the lateral direction, an approximation for small angular
deflections is:

[0427]F2=the force per unit of lateral deflection applied at the
bottom spring seat

[0428]δ2=a unit of lateral deflection

[0429]W=the weight borne by the pendulum

[0430]Lpend.=the length of the pendulum, as undeflected, between the
contact surface of the bearing adapter to the bottom of the pendulum at
the spring seat

[0431]RRocker=r2=the lateral radius of curvature of the rocker
surface

[0432]RSeat=R2=the lateral radius of curvature of the rocker
seat

[0433]Where RSeat and RRocker are of similar magnitude, and are
not unduly small relative to L, the pendulum may tend to have a
relatively large lateral deflection constant. Where RSeat is large
compared to L or RRocker, or both, and can be approximated as
infinite (i.e., a flat surface), this formula simplifies to:

kpendulum=(Flateral/δlateral)=(W/Lpend.)[(RRocker/Lpendulum)+1]

[0434]Using this number in the denominator, and the design weight in the
numerator yields an equivalent pendulum length, Leq.=W
kpendulum

[0435]The sideframe pendulum may have a vertical length measured (when
undeflected) from the rolling contact interface at the upper rocker seat
to the bottom spring seat of between 12 and 20 inches, perhaps between 14
and 18 inches. The equivalent length Leq, may be in the range of
greater than 4 inches and less than 15 inches, and, more narrowly, 5
inches and 12 inches, depending on truck size and rocker geometry.
Although truck 20 or 22 may be a 70 ton special, a 70 ton, 100 ton, 110
ton, or 125 ton truck, truck 20 or 22 may be a truck size having 33 inch
diameter, or 36 or 38 inch diameter wheels. In some embodiments herein,
the ratio of male rocker radius RRocker to pendulum length,
Lpend., may be 3 or less, in some instances 2 or less. In laterally
quite soft trucks this value may be less than 1. The factor
[(1/Lpend.)/((1/RRocker)-(1/RSeat))], may be less than 3,
and, in some instances may be less than 21/2. In laterally quite soft
trucks, this factor may be less than 2. In those various embodiments, the
lateral stiffness of the lateral rocker pendulum, calculated at the
maximum truck capacity, or the GRL limit for the railcar more generally,
may be less than the lateral shear stiffness of the associated spring
group. Further, in those various embodiments the truck may be free of
lateral unsprung bracing, whether in terms of a transom, laterally
extending parallel rods, or diagonally criss-crossing frame bracing or
other unsprung stiffeners. In those embodiments the trucks may have four
cornered damper groups driven by each spring group.

[0436]In the trucks described herein, for their fully laden design
condition which may be determined either according to the AAR limit for
70, 100, 110 or 125 ton trucks, or, where a lower intended lading is
chosen, then in proportion to the vertical sprung load yielding 2 inches
of vertical spring deflection in the spring groups, the equivalent
lateral stiffness of the sideframe, being the ratio of force to lateral
deflection, measured at the bottom spring seat, may be less than the
horizontal shear stiffness of the springs. In some embodiments,
particularly for relatively low density fragile, high valued lading such
as automobiles, consumer goods, and so on, the equivalent lateral
stiffness of the sideframe ksideframe may be less than 6000 lbs./in.
and may be between about 3500 and 5500 lbs./in., and perhaps in the range
of 3700-4100 lbs./in. For example, in one embodiment a 2×4 spring
group has 8 inch diameter springs having a total vertical stiffness of
9600 lbs./in. per spring group and a corresponding lateral shear
stiffness kspring shear of 8200 lbs./in. The sideframe has a rigidly
mounted lower spring seat. It may be used in a truck with 36 inch wheels.
In another embodiment, a 3×5 group of 51/2 inch diameter springs is
used, also having a vertical stiffness of about 9600 lbs./in., in a truck
with 36 inch wheels. It may be that the vertical spring stiffness per
spring group lies in the range of less than 30,000 lbs./in., that it may
be in the range of less than 20,000 lbs./in and that it may perhaps be in
the range of 4,000 to 12000 lbs./in, and may be about 6000 to 10,000
lbs./in. The twisting of the springs may have a stiffness in the range of
750 to 1200 lbs./in. and a vertical shear stiffness in the range of 3500
to 5500 lbs./in. with an overall sideframe stiffness in the range of 2000
to 3500 lbs./in.

[0437]In the embodiments of trucks having a fixed bottom spring seat, the
truck may have a portion of stiffness, attributable to unequal
compression of the springs equivalent to 600 to 1200 lbs./in. of lateral
deflection, when the lateral deflection is measured at the bottom of the
spring seat on the sideframe. This value may be less than 1000 lbs./in.,
and may be less than 900 lbs./in. The portion of restoring force
attributable to unequal compression of the springs may tend to be greater
for a light car as opposed to a fully laden car.

[0438]Some embodiments, including those that may be termed swing motion
trucks, may have one or more features, namely that, in the lateral
swinging direction r/R<0.7; 3''<r<30'', or more narrowly,
4''<r<20''; and 5''<R<45'', or more narrowly,
8''<R<30'', and in lateral stiffness, 2,000 lbs/in
<kpendulum<10,000 lbs/in, or expressed differently, the
lateral pendulum stiffness in pounds per inch of lateral deflection at
the bottom spring seat where vertical loads are passed into the
sideframe, per pound of weight carried by the pendulum, may be in the
range of 0.08 and 0.2, or, more narrowly, in the range of 0.1 to 0.16.

[0439]Friction Surfaces

[0440]Dynamic response may be quite subtle. It is advantageous to reduce
resistance to curving, and self steering may help in this regard. It is
advantageous to reduce the tendency for wheel lift to occur. A reduction
in stick-slip behavior in the dampers may improve performance in this
regard. Employment of dampers having roughly equal upward and downward
friction forces may discourage wheel lift. Wheel lift may be sensitive to
a reduction in torsional linkage between the sideframes, as when a
transom or frame brace is removed. While it may be desirable torsionally
to decouple the sideframes it may also be desirable to supplant a
physically locked relationship with a relationship that allows the truck
to flex in a non-square manner, subject to a bias tending to return the
truck to its squared position such as may be obtained by employing the
larger resistive moment couple of doubled dampers as compared to single
dampers. While use of laterally soft rockers, dampers with reduced stick
slip behavior, four-cornered damper arrangements, and self steering may
all be helpful in their own right, it appears that they may also be
inter-related in a subtle and unexpected manner. Self steering may
function better where there is a reduced tendency to stick slip behavior
in the dampers. Lateral rocking in the swing motion manner may also
function better where the dampers have a reduced tendency to stick slip
behavior. Lateral rocking in the swing motion manner may tend to work
better where the dampers are mounted in a four cornered arrangement.
Counter-intuitively, truck hunting may not worsen significantly when the
rigidly locked relationship of a transom or frame brace is replaced by
four cornered dampers (apparently making the truck softer, rather than
stiffer), and where the dampers are less prone to stick slip behavior.
The combined effect of these features may be surprisingly interlinked.

[0441]In the various truck embodiments described herein, there is a
friction damping interface between the bolster and the sideframes. Either
the sideframe columns or the damper (or both) may have a low or
controlled friction bearing surface, that may include a hardened wear
plate, that may be replaceable if worn or broken, or that may include a
consumable coating or shoe, or pad. That bearing face of the motion
calming, friction damping element may be obtained by treating the surface
to yield desired co-efficients of static and dynamic friction whether by
application of a surface coating, and insert, a pad, a brake shoe or
brake lining, or other treatment. Shoes and linings may be obtained from
clutch and brake lining suppliers, of which one is Railway Friction
Products. Such a shoe or lining may have a polymer based or composite
matrix, loaded with a mixture of metal or other particles of materials to
yield a specified friction performance. Shoes and linings may be
replaceable, as indicated, for example in U.S. Pat. No. 6,374,749 of
Duncan, or U.S. Pat. No. 6,701,850 of McCabe et al, (those documents
being incorporated by reference herein).

[0442]That friction surface may, when employed in combination with the
opposed bearing surface, have a co-efficient of static friction, :s, and
a co-efficient of dynamic or kinetic friction, :k. The coefficients may
vary with environmental conditions. For the purposes of this description,
the friction coefficients will be taken as being considered on a dry day
condition at 70F. In one embodiment, when dry, the coefficients of
friction may be in the range of 0.15 to 0.45, may be in the narrower
range of 0.20 to 0.35, and, in one embodiment, may be about 0.30. In one
embodiment that coating, or pad, may, when employed in combination with
the opposed bearing surface of the sideframe column, result in
coefficients of static and dynamic friction at the friction interface
that are within 20%, or, more narrowly, within 10% of each other. In
another embodiment, the coefficients of static and dynamic friction are
substantially equal. It may be that an elastomeric material may be
employed as described in U.S. Pat. Re 31784 or Re 31,988 both of Wiebe,
(those documents being incorporated herein by reference)

[0443]Sloped Wedge Surface

[0444]Where damper wedges are employed, a generally low friction, or
controlled friction pad or coating may also be employed on the sloped
surface of the damper that engages the wear plate (if such is employed)
of the bolster pocket where there may be a partially sliding, partially
rocking dynamic interaction. A controlled friction interface between the
slope face of the wedge and the inclined face of the bolster pocket, in
which the combination of wear plate and friction member may tend to yield
coefficients of friction of known properties, may be used. A polymeric
surface, or pad having these friction properties may be used, as may a
suitable clutch or brake lining material. In some embodiments those
coefficients may be the same, or nearly the same, and may have little or
no tendency to exhibit stick-slip behavior, or may have a reduced
stick-slip tendency as compared to cast iron on steel. Further, the use
of brake linings, or inserts of cast materials having known friction
properties may tend to permit the properties to be controlled within a
narrower, more predictable and more repeatable range such as may yield a
reasonable level of consistency in operation. The coating, or pad, or
lining, may be a polymeric element, or an element having a polymeric or
composite matrix loaded with suitable friction materials. It may be
obtained from a brake or clutch lining manufacturer, or the like. One
such firm that may be able to provide such friction materials is Railway
Friction Products of 13601 Laurinburg Maxton Ai, Maxton N.C.; another may
be Quadrant EPP USA Inc., of 2120 Fairmont Ave., Reading Pa. In one
embodiment, the material may be the same as that employed by the Standard
Car Truck Company in the "Barber Twin Guard"® damper wedge with
polymer covers. In one embodiment the material may be such that a
coating, or pad, may, when employed with the opposed bearing surface of
the sideframe column, result in coefficients of static and dynamic
friction at the friction interface that are within 20%, or more narrowly,
within 10% of each other. In another embodiment, the coefficients of
static and dynamic friction are substantially equal. The co-efficient of
dynamic friction may be in the range of 0.15 to 0.30, and in one
embodiment may be about 0.20.

[0445]A damper may be provided with a friction specific treatment, whether
by coating, pad or lining, on both the vertical friction face and the
slope face. The coefficients of friction on the slope face need not be
the same as on the friction face, although they may be. In one embodiment
it may be that the coefficients of static and dynamic friction on the
friction face may be about 0.3, and may be about equal to each other,
while the coefficients of static and dynamic friction on the slope face
may be about 0.2, and may be about equal to each other. In either case,
whether on the vertical bearing face against the sideframe column, or on
the sloped face in the bolster pocket, the present inventors consider it
to be advantageous to avoid surface pairings that may tend to lead to
galling, and stick-slip behavior.

[0446]Spring Groups

[0447]The main spring groups may have a variety of spring layouts. Among
various double damper embodiments of spring layout are the following:

[0449]In the context of 100 Ton or 110 Ton trucks, the inventors propose
spring and damper combinations lying within 20% (and preferably within
10%) of the following parameter envelopes: [0450](a) For a four wedge
arrangement with all steel or iron damper surfaces, an envelope having an
upper boundary according to kdamper=2.41(θwedge)1.76, and
a lower boundary according to kdamper=1.21(θwedge)1.76.
[0451](b) For a four wedge arrangement with all steel or iron damper
surfaces, a mid range zone of

[0451]kdamper=1.81(θwedge)1.76(+/-20%). [0452](c) For a
four wedge arrangement with non-metallic damper surfaces, such as may be
similar to brake linings, an envelope having an upper boundary according
to kdamper=4.84(θwedge)1.64, and a lower a lower boundary
according to kdamper=2.42(θwedge)1.64 where the wedge
angle may lie in the range of 30 to 60 degrees. [0453](d) For a four
wedge arrangement with non-metallic damper surfaces, a mid range zone of

[0453]kdamper=3.63(θwedge)1.64(+/-20%).

[0454]Where kdamper is the side spring stiffness under each damper in
lbs/in/damper [0455]θwedge--is the associated primary wedge
angle, in degrees

[0456]θwedge may tend to lie in the range of 30 to 60 degrees.
In other embodiments θwedge may lie in the range of 35-55
degrees, and in still other embodiments may tend to lie in the narrower
range of 40 to 50 degrees.

[0457]In some embodiments the upward and downward damping forces may be
not overly dissimilar, and may in some cases tend to be roughly equal.
Frictional forces at the dampers may differ depending on whether the
damper is being loaded or unloaded. The angle of the wedge, the
coefficients of friction, and the springing under the wedges can be
varied. A damper is being "loaded" when the bolster is moving downward in
the sideframe window, since the spring force is increasing, and hence the
force on the damper is increasing. Similarly, a damper is being
"unloaded" when the bolster is moving upward toward the top of the
sideframe window, since the force in the springs is decreasing. The
equations can be written as:

[0460]Where: Fd=friction force on the sideframe column
[0461]Fs=force in the spring [0462]μs=coefficient of
friction on the angled slope face on the bolster [0463]μc=the
coefficient of friction against the sideframe column [0464]Φ=the
included angle between the angled face on the bolster and the friction
face bearing against the column

[0465]For a given angle, a friction load factor, Cf can be determined
as Cf=Fd/Fs. This load factor Cf will tend to be
different depending on whether the bolster is moving up or down.

[0466]In some embodiments there may be spring groups that have different
vertical spring rates in the empty and fully loaded conditions. To that
end springs of different heights may be employed, for example, to yield
two or more vertical spring rates for the entire spring group. In this
way, the dynamic response in the light car condition may be different
from the dynamic response in a fully loaded car, where two spring rates
are used. Alternatively, if three (or more) spring rates are used, there
may be an intermediate dynamic response in a semi-loaded condition. In
one embodiment, each spring group may have a first combination of springs
that have a free length of at least a first height, and a second group of
springs of which each spring has a free length that is less than a second
height, the second height being less than the first height by a distance
δ1, such that the first group of springs will have a range of
compression between the first and second heights in which the spring rate
of the group has a first value, namely the sum of the spring rates of the
first group of springs, and a second range in which the spring rate of
the group is greater, namely that of the first group plus the spring rate
of at least one of the springs whose free height is less than the second
height. The different spring rate regimes may yield corresponding
different damping regimes.

[0467]For example, in one embodiment a car having a dead sprung weight
(i.e., the weight of the car body with no lading, and excluding the
unsprung weight below the main springs such as the sideframes and
wheelsets), of about 35,000 to about 55,000 lbs (+/-5000 lbs) may have
spring groups of which a first portion of the springs have a free height
in excess of a first height. The first height may, for example be in the
range of about 93/4 to 101/4 inches. When the car sits, unladen, on its
trucks, the springs compress to that first height. When the car is
operated in the light car condition, that first portion of springs may
tend to determine the dynamic response of the car in the vertical bounce,
pitch-and-bounce, and side-to-side rocking, and may influence truck
hunting behavior. The spring rate in that first regime may be of the
order of 12,000 to 22,000 lbs/in., and may be in the range of 15,000 to
20,000 lbs/in.

[0468]When the car is more heavily laden, as for example when the
combination of dead and live sprung weight exceeds a threshold amount,
which may correspond to a per car amount in the range of perhaps 60,000
to 100,000 lbs, (that is, 15,000 to 25,000 lbs per spring group for
symmetrical loading, at rest) the springs may compress to, or past, a
second height. That second height may be in the range of perhaps 81/2 to
93/4 inches, for example. At this point, the sprung weight is sufficient
to begin to deflect another portion of the springs in the overall spring
group, which may be some or all of the remaining springs, and the spring
rate constant of the combined group of the now compressed springs in this
second regime may tend to be different, and larger than, the spring rate
in the first regime. For example, this larger spring rate may be in the
range of about 20,000-30,000 lbs/in., and may be intended to provide a
dynamic response when the sum of the dead and live loads exceed the
regime change threshold amount. This second regime may range from the
threshold amount to some greater amount, perhaps tending toward an upper
limit, in the case of a 110 Ton truck, of as great as about 130,000 or
135,000 lbs per truck. For a 100 Ton truck this amount may be 115,000 or
120,000 lbs per truck.

[0469]Table 1 gives a tabulation of a number of spring groups that may be
employed in a 100 or 110 Ton truck, in symmetrical 3×3 spring
layouts and that include dampers in four-cornered groups. The last entry
in Table 1 is a symmetrical 2:3:2 layout of springs. The term "side
spring" refers to the spring, or combination of springs, under each of
the individually sprung dampers, and the term "main spring" referring to
the spring, or combination of springs, of each of the main coil groups:

[0470]In this tabulation, the terms NSC-1, NSC-2, D8, D8A and D6B refer to
springs of non-standard size. The properties of these springs are given
in Table 2a (main springs) and 2b (side springs), along with the
properties of the other springs of Table 1.

[0472]In Table 3, the Main Spring entry has the format of the quantity of
springs, followed by the type of spring. For example, the ASF Super
Service Ride Master, in one embodiment, has 7 springs of the D5 Outer
type, 7 springs of the D5 Inner type, nested inside the D5 Outers, and 2
springs of the D6A Inner-Inner type, nested within the D5 Inners of the
middle row (i.e., the row along the bolster centerline). It also has 2
side springs of the 5052 Outer type, and 2 springs of the 5063 Inner type
nested inside the 5062 Outers. The side springs would be the middle
elements of the side rows underneath centrally mounted damper wedges.
[0473]kempty refers to the overall spring rate of the group in
lbs/in for a light (i.e., empty) car. [0474]kloaded refers to the
spring rate of the group in lbs/in., in the fully laded condition.
[0475]"Solid" refers to the limit, in lbs, when the springs are
compressed to the solid condition [0476]HEmpty refers to the height
of the springs in the light car condition [0477]HLoaded refers to
the height of the springs in the at rest fully loaded condition
[0478]kw refers to the overall spring rate of the springs under the
dampers. [0479]kw/kloaded gives the ratio of the spring rate of
the springs under the dampers to the total spring rate of the group, in
the loaded condition, as a percentage.

[0480]The wedge angle is the primary angle of the wedge, expressed in
degrees.

[0481]FD is the friction force on the sideframe column. It is given
in the upward and downward directions, with the last row giving the total
when the upward and downward amounts are added together.

[0482]In various embodiments of trucks, such as truck 20 or 22, the
resilient interface between each sideframe and the end of the truck
bolster associated therewith may include a four cornered damper
arrangement and a 3×3 spring group having one of the spring
groupings set forth in Table 1. Those groupings may have wedges having
primary angles lying in the range of 30 to 60 degrees, or more narrowly
in the range of 35 to 55 degrees, more narrowly still in the range 40 to
50 degrees, or may be chosen from the set of angles of 32, 36, 40 or 45
degrees. The wedges may have steel surfaces, or may have friction
modified surfaces, such as non-metallic surfaces.

[0483]The combination of wedges and side springs may be such as to give a
spring rate under the side springs that is 20% or more of the total
spring rate of the spring groups. It may be in the range of 20 to 30% of
the total spring rate. In some embodiments the combination of wedges and
side springs may be such as to give a total friction force for the
dampers in the group, for a fully laden car, when the bolster is moving
downward, that is less than 3000 lbs. In other embodiments the arithmetic
sum of the upward and downward friction forces of the dampers in the
group is less than 5500 lbs.

[0484]In some embodiments in which steel faced dampers are used, the sum
of the magnitudes of the upward and downward friction forces may be in
the range of 4000 to 5000 lbs. In some embodiments, the magnitude of the
friction force when the bolster is moving upward may be in the range of
2/3 to 3/2 of the magnitude of the friction force when the bolster is
moving downward. In some embodiments, the ratio of Fd(Up)/Fd (Down) may
lie in the range of 3/4 to 5/4. In some embodiments the ratio of
Fd(Up)/Fd(Down) may lie in the range of 4/5 to 6/5, and in some
embodiments the magnitudes may be substantially equal.

[0485]In some embodiments in which non-metallic friction surfaces are
used, the sum of the magnitudes of the upward and downward friction force
may be in the range of 4000 to 5500 lbs. In some embodiments, the
magnitude of the friction force when the bolster is moving up, Fd(Up), to
the magnitude of the friction force when the bolster is moving down,
Fd(Down) may be in the range of 3/4 to 5/4, may be in the range of 0.85
to 1.15. Further, those wedges may employ a secondary angle, and the
secondary angle may be in the range of about 5 to 15 degrees.

[0486]Nos. 1 and 2

[0487]The truck embodiment identified as No. 1 may be taken to employ
damper wedges in a four-cornered arrangement in which the primary wedge
angle is 45 degrees (+/-) and the damper wedges have steel on steel
bearing surfaces. In the second instance, the truck embodiment identified
as No. 2, may be taken to employ damper wedges in a four-cornered
arrangement in which the primary wedge angle is 40 degrees (+/-), and the
damper wedges have non-metallic bearing surfaces. No. 2 may employ
non-metallic friction surfaces, that may tend not to exhibit stick-slip
behavior, for which the resultant static and dynamic friction
coefficients are substantially equal. The friction coefficients of the
friction face on the sideframe column may be about 0.3. The slope
surfaces of the wedges may also work on a non-metallic bearing surface
and may also tend not to exhibit stick slip behavior. The coefficients of
static and dynamic friction on the slope face may also be substantially
equal, and may be about 0.2. Those wedges may have a secondary angle, and
that secondary angle may be about 10 degrees. No. 3

[0488]In some embodiments there may be a 2:3:2 spring group layout. In
this layout the damper springs may be located in a four cornered
arrangement in which each pair of damper springs is not separated by an
intermediate main spring coil, and may sit side-by-side, whether the
dampers are cheek-to-cheek or separated by a partition or intervening
block. There may be three main spring coils, arranged on the longitudinal
centerline of the bolster. The springs may be non-standard springs, and
may include outer, inner, and inner-inner springs identified respectively
as D51-O, D61-I, and D61-A in Tables 1, 2 and 3 above. The No. 3 layout
may include wedges that have a steel-on-steel friction interface in which
the kinematic friction co-efficient on the vertical face may be in the
range of 0.30 to 0.40, and may be about 0.38, and the kinematic friction
co-efficient on the slope face may be in the range of 0.12 to 0.20, and
may be about 0.15. The wedge angle may be in the range of 45 to 60
degrees, and may be about 50 to 55 degrees. In the event that 50 (+/-)
degree wedges are chosen, the upward and downward friction forces may be
about equal (i.e., within about 10% of the mean), and may have a sum in
the range of about 4600 to about 4800 lbs, which sum may be about 4700
lbs (+/-50). In the event that 55 degree (+/-) wedges are chosen, the
upward and downward friction forces may again be substantially equal
(within 10% of the mean), and may have a sum on the range of 3700 to 4100
Lbs, which sum may be about 3850-3900 lbs.

[0489]Alternatively, in other embodiments employing a 2:3:2 spring layout,
non-metallic wedges (i.e., wedges having non-metallic friction linings,
pads or coatings, typically mounted to a cast iron or steel damper wedge
body) may be employed. Those wedges may have a vertical face to sideframe
column co-efficient of kinematic friction in the range of 0.25 to 0.35,
and which may be about 0.30. The slope face co-efficient of kinematic
friction may be in the range of 0.08 to 0.15, and may be about 0.10. A
wedge angle of between about 35 and about 50 degrees may be employed. It
may be that the wedge angles lie in the range of about 40 to about 45
degrees. In one embodiment in which the wedge angle is about 40 degrees,
the upward and downward kinematic friction forces may have magnitudes
that are each within about 20% of their average value, and whose sum may
lie in the range of about 5400 to about 5800 lbs, and which may be about
5600 lbs (+/-100). In another embodiment in which the wedge angle is
about 45 degrees, the magnitudes of each of the upward and downward
forces of kinematic friction may be within 20% of their averaged value,
and whose sum may lie in the range of about 440 to about 4800 lbs, and
may be about 4600 lbs (+/-100).

[0490]Combinations and Permutations

[0491]The present description recites many examples of dampers and bearing
adapter arrangements. Not all of the features need be present at one
time, and various optional combinations can be made. As such, the
features of the embodiments of several of the various figures may be
mixed and matched, without departing from the spirit or scope of the
invention. For the purpose of avoiding redundant description, it will be
understood that the various damper configurations can be used with spring
groups of a 2×4, 3×3, 3:2:3, 2:3:2, 3×5 or other
arrangement. Similarly, several variations of bearing to pedestal seat
adapter interface arrangements have been described and illustrated. There
are a large number of possible combinations and permutations of damper
arrangements and bearing adapter arrangements. In that light, it may be
understood that the various features can be combined, without further
multiplication of drawings and description.

[0492]The various embodiments described herein may employ self-steering
apparatus in combination with dampers that may tend to exhibit little or
no stick-slip behavior. They may employ a "Pennsy" pad, or other
elastomeric pad arrangement, for providing self-steering. Alternatively,
they may employ a bi-directional rocking apparatus, which may include a
rocker having a bearing surface formed on a compound curve of which
several examples have been illustrated and described herein. Further
still, the various embodiments described herein may employ a four
cornered damper wedge arrangement, which may include bearing surfaces of
a non-stick-slip nature, in combination with a self steering apparatus,
and in particular a bi-directional rocking self-steering apparatus, such
as a compound curved rocker.

[0493]In the various embodiments of trucks herein, the gibs may be shown
mounted to the bolster inboard and outboard of the wear plates on the
side frame columns. In some of the embodiments the clearance between the
bolster gibs and the side frames may be sufficient to permit a motion
allowance of at least 3/4'' of lateral travel of the truck bolster
relative to the wheels to either side of neutral, advantageously permits
greater than 1 inch of travel to either side of neutral, and may permit
travel in the range of about 1 or 11/8'' to about 15/8 or 1 9/16'' inches
to either side of neutral.

[0494]In one embodiment there may be a combination of a bi-directional
compound curvature rocker surface, a four cornered damper arrangement in
which the dampers are provided with friction linings that may tend to
exhibit little or no stick-slip behavior, and may have a slope face with
a relatively low friction bearing surface. However, there are many
possible combinations and permutations of the features of the examples
shown herein. In general it is thought that a self draining geometry may
be preferable over one in which a hollow is formed and for which a drain
hole may be required.

[0495]In each of the trucks shown and described herein, the overall ride
quality may depend on the inter-relation of the spring group layout and
physical properties, or the damper layout and properties, or both, in
combination with the dynamic properties of the bearing adapter to
pedestal seat interface assembly. The lateral stiffness of the sideframe
acting as a pendulum may be less than the lateral stiffness of the spring
group in shear. In rail road cars having 110 ton trucks, one embodiment
may employ trucks having vertical spring group stiffnesses in the range
of 16,000 lbs/inch to 36,000 lbs/inch in combination with an embodiment
of bi-directional bearing adapter to pedestal seat interface assemblies
as shown and described herein. In another embodiment, the vertical
stiffness of the spring group may be less than 12,000 lbs./in per spring
group, with a horizontal shear stiffness of less than 6000 lbs./in.

[0496]The double damper arrangements shown above can also be varied to
include any of the four types of damper installation indicated at page
715 in the 1997 Car and Locomotive Cyclopedia, whose information is
incorporated herein by reference, with appropriate structural changes for
doubled dampers, with each damper being sprung on an individual spring.
That is, while inclined surface bolster pockets and inclined wedges
seated on the main springs have been shown and described, the friction
blocks could be in a horizontal, spring biased installation in a pocket
in the bolster itself, and seated on independent springs rather than the
main springs. Alternatively, it is possible to mount friction wedges in
the sideframes, in either an upward orientation or a downward
orientation.

[0497]The embodiments of trucks shown and described herein may vary in
their suitability for different types of service. Truck performance can
vary significantly based on the loading expected, the wheelbase, spring
stiffnesses, spring layout, pendulum geometry, damper layout and damper
geometry.

[0498]Various embodiments of the invention have been described in detail.
Since changes in and or additions to the above-described best mode may be
made without departing from the nature, spirit or scope of the invention,
the invention is not to be limited to those details but only by the
appended claims.